WAR DEPARTMENT TECHNICAL MANUAL
Ch, Quality & Reliability Branch
ORDNANCE MAINTENANCE
Ordnance Engine Model R975-C4
(Continental)
WAR DEPARTMENT • 27 JANUARY 1944
FOR ORDNANCE PERSONNEL ONLY
‘M
ZC
WAR DEPARTMENT TECHNICAL MANUAL
*TM 9-1725
ORDNANCE MAINTENANCE
Ordnance Engine Model R975-C4
(Continental)
WAR DEPARTMENT
27 JANUARY 1944
*This manual includes pertinent information from TB 1700-4, dated 1 January 1942
and TB' 1700-24, dated 15 May 1943.
WAR DEPARTMENT
Washington 25, D. C., 27 January 1944
TM 9-1725, Ordnance Maintenance: Ordnance Engine Model
R975-C4 (Continental), is published for the information and guidance
of all concerned.
I" A.G. 300.7 (29 Sep 43) ]
I O.O.M. 461/(TM 9) Rar. Ars. (28 Jan 44) J
By order of the Secretary of War:
G. C. MARSHALL,
Chief of Staff.
Official:
J. A. ULIO,
Major General,
The Adjutant General.
Distribution: R 9 (4); Bn 9 (2); C 9 (5).
(For explanation of symbols, see FM 21-6.)
TM 9-1725
CHAPTER 1.
CHAPTER 2.
CHAPTER 3.
CHAPTER 4.
Section I.
II.
III.
IV.
V.
VI.
VII.
VIII.
IX.
X.
XI.
XII.
XIII.
XIV.
XV.
CHAPTER 5.
CHAPTER 6.
CHAPTER 7.
CHAPTER 8.
REFERENCES
INDEX
CONTENTS
Paragraphs
Introduction 1-2
Engine Description and Data 3- 4
Disassembly of Engine into
Subassemblies 5-10
Disassembly, Cleaning, In-
spection, Repair, and Assem-
bly of Subassemblies 11-74
Introduction 11—14
Front crankcase section and front
main bearing support 15-18
Main crankcase section 19-22
Cylinders, valves, and valve oper-
ating mechanisms 23-26
Pistons 27-30
Crankshaft and master rod ... 31-34
Articulated rods and knuckle pins 35-37
Crankshaft gear assembly 38-40
Diffuser section 41—44
Rear crankcase section 45—48
Oil pump 49-53
Rear crankcase section subas-
semblies 54-62
Ignition harness 63-65
Flywheel and fan 66—69
Miscellaneous subassemblies . . 70-74
Assembly of Subassemblies. . 75-79
Tests and Adjustments 80-83
Fits and Tolerances 84-90
Tools 91-92
Pages
4- 7
8- 29
30- 81
82-193
82- 85
86 - 88
88-100
100-113
113-117
117-136
136-140
140- 141
141- 162
162-171
171-178
179-186
186-190
190-192
192-193
194-245
245-248
249-258
259-261
262-263
264-271
3
TM 9-1725
1
ORDNANCE MAINTENANCE - ORDNANCE ENGINE
MODEL R975-C4 (CONTINENTAL)
CHAPTER 1
INTRODUCTION
Paragraph
Scope 1
Modification work order (MWO) and major unit assembly
replacement record 2
1. SCOPE.
a. The instructions contained in this manual are for the informa-
tion and guidance of personnel charged with the maintenance and
repair of the Continental R975-C4 Tank Engine. These instructions
are supplementary to field and technical manuals prepared for the
using arms. This manual does not contain information which is
intended primarily for the using arms, since such information is
figure I — Front View of Engine
4
TM 9-1725
1-2
INTRODUCTION
Figure 2 — Front View of Engine with Cowling, Clutch, Flywheel,
Fan, and Engine Front Support Bar Removed
available to ordnance maintenance personnel in 100-series TM’s
or FM’s.
1». This manual contains a description of, and procedure for the
disassembly, cleaning, inspection, repair, and assembly of this engine
and its components, except accessories such as carburetor, magneto,
starter, generator, and fuel pump. TM’s covering these accessories
are listed in paragraph 62 of this manual.
2. MODIFICATION WORK ORDER (MWO) AND MAJOR UNIT
ASSEMBLY REPLACEMENT RECORD.
a. Description. Every vehicle is supplied with a copy of AGO
Form No. 478 which provides a means of keeping a record of each
MWO completed or major unit assembly replaced. This form in-
5
TM 9-1725
2
ORDNANCE MAINTENANCE - ORDNANCE ENGINE
MODEL R975-C4 (CONTINENTAL)
RA PD 314776
Figure 3 — Left Rear View of Engine
eludes spaces for the vehicle name and U. S. A. Registration Number,
instructions for use, and information pertinent to the work accom-
plished. It is very important that the form be used as directed and
that it remain with the vehicle until the vehicle is removed from
service.
b. Instructions for Use. Personnel performing modifications or
major unit assembly replacements must record clearly on the form
a description of the work completed and must initial the form in the
columns provided. When each modification is completed, record the
date, hours and/or mileage, and MWO number. When major unit
assemblies, such as engines, transmissions, and transfer cases, are re-
6
TM 9-1725
3
ORDNANCE MAINTENANCE - ORDNANCE ENGINE
MODEL R975-C4 (CONTINENTAL)
CHAPTER 2
ENGINE DESCRIPTION AND DATA
Paragraph
Description 3
Data 4
3. DESCRIPTION.
a. General. The Model R975-C4 Tank Engine is a single-row,
9-cylinder, static radial, air-cooled type engine, operating on the con-
ventional 4-stroke cycle. The engine has a 5-inch bore and a 5.5-inch
stroke with a total piston displacement of 973 cubic inches. With
a compression ratio of 5.7 to 1, the engine develops a brake horse-
power of 485 at 2,400 revolutions per minute. The main components
of the engine are the crankcase, cylinder and valve assemblies, con-
necting rod and crankshaft assemblies, accessory drives and accesso-
ries, and the ignition, fuel, and lubricating systems.
b. Designations. Throughout this manual the flywheel end of
the engine is designated as the “front”, and the accessory end as the
“rear.” The “right” and “left” sides of the engine are as viewed from
the rear. Horizontal and vertical positions of the engine are referred
to with respect to the position of the crankshaft. Directions of
rotation are determined by looking from the rear toward the front of
the engine, or in the case of side drives, by looking toward the crank-
shaft. The cylinders are numbered in a clockwise direction, the top
cylinder being number one. Following this designation, the firing
order of the cylinders is 1, 3, 5, 7, 9, 2, 4, 6, 8.
c. Crankcase.
(1) General. The crankcase is the main body around which the
engine is built. It is composed of five flanged, cast aluminum-alloy
sections secured together by studs, flat washers, and nuts, fastened
with lock wire. The five components are the front, front main bear-
ing support, main, diffuser, and rear crankcase sections.
(2) Front Crankcase Section. The front crankcase section is
a conical-shaped casting which houses the main thrust ball bearing
and the mounting clamp for the engine front support bar (fig. 5). The
front cover, which serves as a retainer for the main thrust bearing, is
mounted to the front crankcase section over seven studs. The cover
is secured to this section by flat washers and castellated nuts fastened
with lock wire.
(3) Front Main Bearing Support. This section is a flat,
aluminum-alloy casting which serves as a bulkhead between the front
and main crankcase sections and supports the roller-type front main
bearing (fig. 5).
8
TM 9-1725
3
ENGINE DESCRIPTION AND DATA
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Figure 5 — Crankcase Sections
TM 9-1725
3
ORDNANCE MAINTENANCE - ORDNANCE ENGINE
MODEL R975-C4 (CONTINENTAL)
(4) Main Crankcase Section. The main crankcase section
casting has cylinder mounting pads and hold-down studs to support
the cylinder assemblies. The section also supports the rear main
bearing, and houses the cam ring, valve tappets and rollers, and valve
tappet guides (fig. 5). The front crankcase section and front main
bearing support are secured to the main crankcase section over stdds
anchored in the main section forward flange. The sections are
attached by means of flat washers and castellated nuts installed over
the studs. The tightened nuts are fastened with lock wire.
(5) Diffuser Section. The crankcase diffuser section is a flat
casting which separates the main crankcase area from the diffuser and
distribution chambers in the rear crankcase section (fig. 5). The
diffuser section supports the diffuser ring, diffuser impeller and the
drive mechanism, starter gear, two accessory drive idler gears, and
the accessory drive gears. The directional vanes of the impeller aid
in better distribution of the fuel mixture through the troughs in the
diffuser ring, into the fuel induction tubes, and then into the cylinders.
Three bushings project from the rear of the diffuser section. These
bushings' support those portions of the starter gear and accessory
drive shafts which pass through the distribution chamber. The shafts
extend through the distribution chamber to the rear crankcase section.
(6) Rear Crankcase Section. The rear crankcase section sup-
ports the accessory drive shafts and provides mounting pads for the
various engine accessories. The forward end of the rear crankcase
section forms the rear wall of the diffuser and distribution chambers
and provides connections for the fuel induction tubes. Mounting
bosses for the rear engine support are cast integral with the fuel
induction tube connections. The diffuser and main crankcase sec-
tions are mounted over studs in the rear crankcase section forward
flange, and are secured to the rear section by plain washers and
castellated nuts mounted over the studs. The tightened nuts are
fastened with lock wire.
(7) Crankcase Breather. A crankcase breather system is pro-
vided for engine ventilation, A breather is attached to the rocker
boxes of two cylinders by means of clamps and bolts (fig. 3). The
breather is connected to openings in the main and rear crankcase
sections by hose.
d. Cowling. The cowling is made up of three sections, the upper
and lower segments, and the cowling ring (fig. 241). The cowling ring
is attached to the engine, and the cowling sections are attached to the
ring and to mounting bosses on cylinder rocker boxes. The cowling
and intercylinder baffles attached to the cowling give direction to the
air passing over the engine and help cool the engine.
10
ENGINE DESCRIPTION AND DATA
TM 9-1725
3
FLAT WASHER -
ROCKER BOX COVER
RUBBER SEAL
LOCK WASHER
COVER GASKET
VALVE GUIDE
GASKET -
FLAT — y
WASHERN
WASHER
PACKING NUT
DRAIN TUBE-
CYLINDER
ASSEMBLY
EXHAUST ELBOW
FLAT WASHER - 1
CASTELLATED NUT-
INDUCTION TUBE *- CYLINDER BASE PACKING
GLAND NUT
— RUBBER SEAL
RA PD 314800
Figure 6 — Cylinder Disassembled
11
TM 9-1725
3
ORDNANCE MAINTENANCE - ORDNANCE ENGINE
MODEL R975-C4 (CONTINENTAL)
e. Cylinders.
(1) General. Each of the nine cylinders in the engine consists
of a cast aluminum head, cast aluminum cooling muff, and forged
steel barrel.
(2) Cylinder Heads and Barrels. Both the cast aluminum
cylinder heads and muffs are finned to promote rapid cooling. The
fins are cast integral with the heads and muffs. The cylinder muff is
shrunk onto the steel cylinder barrel, after which the head is screwed
onto the barrel over barrel threads treated with sealing compound
to prevent leakage. Two rocker arm support boxes are cast integral
with each cylinder head (fig. 6). Openings are provided in both the
front and rear of each cylinder head for the insertion of spark plugs,
and there is an intake and exhaust port in each cylinder head.
Cylinders are secured to cylinder mounting pads on the main crank-
case section by cylinder barrel flanges installed over studs in the
mounting pads. Hold-down nuts are installed on the studs, tightened,
and fastened securely.
(3) Intake and Exhaust Ports. The intake port in each cylin-
der faces the rear of the cylinder. Intake ports are provided with
three tapped screw holes. Fuel induction tubes are secured to the
ports with cap screws installed through these holes (fig. 6). Use of
cap screws is made possible by phosphor bronze wire threads in
the screw holes. Exhaust ports face the side of each cylinder.
These ports are machined to receive a finned exhaust elbow (fig. 6),
and are equipped with four mounting studs over which the elbows
are installed. The elbows are secured by flat washers, and castellated
nuts which are tightened and fastened securely with lock wire.
(4) Valve Guides and Valve Seat Inserts. Bronze valve
guides are shrunk into bosses cast integral with the cylinders, inside
the valve ports (fig. 6). Valve seat inserts are shrunk into the inside
of each cylinder head at an angle, providing a hemispherical com-
bustion chamber within the cylinder. Intake valve inserts are made
of bronze; exhaust valve seats are made of steel.
(5) Rocker Boxes. Each rocker box has four studs over which
rocker box covers are installed. Covers are secured to the boxes by
flat washers, lock washers, and nuts (fig. 6). Bosses are cast at both
the front and rear ends of each rocker box. The engine cowling is
mounted to these bosses (par. 3 d). Push rod housing connec-
tions are screwed into the rear under side of the rocker box housings.
f. Pistons, Piston Pins, and Rings.
(1) Pistons. Forged aluminum alloy pistons are of the full-trunk
type (fig. 7). The under side of all piston heads is ribbed to provide
increased strength and promote quicker cooling.
(2) Piston Pins. Steel piston pins are of the full-floating type,
12
TM 9-1725
3
ENGINE DESCRIPTION AND DATA
PISTON
MASTER ROD
KNUCKLE PIN LOCK
LOCK FOR SCREW
KNUCKLE PIN LOCK
SCREW
CRANKSHAFT
COUNTERWEIGHTS
RA PD 314696
Figure 7 — Crankshaft, Connecting Rods, Piston, and Knuckle
Pin Assembly
and are positioned in the pistons by soft aluminum plugs (fig. 109).
The plugs are held in place by the cylinder walls.
(3) Piston Rings. Five piston rings are used in each piston,
three compression rings (one of which is a chrome-plated ring), and
one oil ring above, and one below the piston pin (fig. 7). The
top compression ring is chrome-plated. The next two compression
rings are taper-faced to provide easier seating of the rings in the
cylinder barrels.
g. Valve Operating Mechanisms.
(1) General. Each intake and exhaust valve operating mecha-
nism consists of a valve tappet roller, valve tappet, tappet guide, push
rod, push rod housing, and rocker arm assembly (fig. 235). The
valves are actuated through these mechanisms by a cam ring (fig. 235)
which is rotated by means of a train of gears. As the cam rotates,
the cam lobes raise the valve tappets which raise the push rods. The
push rods, in turn, operate the rocker arms which open the valves.
13
TM 9-1725
3
ORDNANCE MAINTENANCE - ORDNANCE ENGINE
MODEL R975-C4 (CONTINENTAL)
(2) Cam. The circular cam (fig. 235) is secured to the rear main
bearing extension by the cam hub bearing support. The cam is
driven through a train of gears by the crankshaft gear. The crank-
shaft gear turns a pinion gear on the front of the starter drive shaft
which, in turn, meshes with the spur gear on the cam, causing the
cam to rotate.
(3) Valve Tappets and Tappet Guides. Valve tappets and
valve tappet guides are located around the rear outside wall of the
main crankcase section (fig. 75). Each tappet has a roller which
rides the cam lobes and moves the tappet. Each tappet moves
through its closely fitted guide. Each tappet has a socket and spring
at the push rod end to provide a seat for the ball end of the push rod
(fig. 235).
(4) Push Rods. Push rods consist of a heat-treated seamless
steel tube, and two stemmed, hardened steel balls. The stems of the
balls are pressed into the ends of the tube. One ball end of each
push rod fits into valve tappet socket, and the other ball end into a
similar socket incorporated in the adjusting screw at the push rod end
of each rocker arm (fig. 235).
(5) Rocker Arms (fig. 236). Rocker arms are of one-section
machined steel forgings. They are mounted on a double roller bear-
ing. The inner bearing race is clamped in the rocker box by a through
bolt. The valve end of the rocker arm is forked to carry a roller.
The roller operates on a hub and pin riveted into the rocker arm.
When moved, the rocker arm contacts the valve stem through this
roller and moves the valve. Tappet clearance is adjusted by an
adjusting screw and adjusting screw lock nut at the push rod end of
the rocker arm.
(6) Valves and Springs (fig. 108). Intake and exhaust valves
are machined, heat-resistant steel forgings. The exhaust valves have
a hollow stem containing sodium which serves as a valve coolant. The
intake valve stem is solid and slightly smaller in diameter than the
exhaust valve stem. Three valve springs over each valve stem are
seated on a washer at the base of each rocker box. These springs
are held in place by a shouldered washer secured in position by a split
lock on the valve stem.
h. Connecting Rod Assemblies.
(1) General. The nine pistons in the engine are connected to
the crankshaft by means of a master rod and eight articulated rods
(fig- 7).
(2) Master Rod. The master rod is connected to the No. 1
cylinder piston pin and the crankshaft crankpin (fig. 7). The rod is
finish-machined from H-section, forged, chrome-nickel steeL The
master rod has a steel-backed, silver-lead bearing in the crankshaft
14
TM 9-1725
3
ENGINE DESCRIPTION AND DATA
COUNTERWEIGHT
PINS U DAMPER COUNTERWEIGHT RAPD 314713
Figure 8 — Crankshaft Sections
end, and a bronze bushing in the piston pin end. The master rod has
widened flanges at the crankshaft end. These flanges are bored to
receive the articulated rod knuckle pins which connect the articulated
rods to the master rod.
(3) Articulated Rods (fig. 7). Articulated, or connecting rods,
are also finish-machined from H-section, forged chrome-nickel steel.
The rods are connected to the piston by piston pins and to the master
rod by knuckle pins. The piston pin and knuckle pin bushings in the
ends of the articulated rods are of bronze.
i. Crankshaft.
(1) General. The crankshaft is a two-piece, single-throw, coun-
terbalanced assembly, machined from nickel-steel forgings. The
crankshaft consists of a front and a rear section. Each crankshaft
section has a crankcheek and counterweight. The rear section coun-
terweight is the dynamic damper designed to minimize crankshaft
vibration (fig. 8). The crankcheek and counterweight in both sections
have an alining hole. An alining bar is installed through these holes
when crankshaft sections are being assembled to insure proper aline-
ment (fig. 134).
(2) Front Crankshaft Section. The front section consists of
the crankshaft, the front crankcheek with its counterweight, and the
crankpin. The front end of the crankshaft is splined (S.A.E. spline
No. 30) to receive the flywheel hub. The front end is also threaded
for the thrust bearing retaining nut. The front crankcheek has an
15
TM 9-1725
3
ORDNANCE MAINTENANCE - ORDNANCE ENGINE
MODEL R975-C4 (CONTINENTAL)
extension below the centerline of the shaft proper to support a steel
counterweight. The crankpin has an oil passage drilled through it
lengthwise. There is also a small oil passage in the clamping end of
the front crankshaft section. Oil squirts through this passage under
pressure to the cylinder walls as the crankshaft revolves.
(3) Rear Crankshaft Section. The rear crankshaft section
consists of the rear crankcheek with the dynamic damper counter-
weight, and the rear main bearing journal (fig. 8). The rear crank-
cheek is bored to receive the crankpin. It is also bored and tapped to
receive the clamping cap screw, and is slotted at the top crankpin end
to permit the clamping action of the cap screw. The crankshaft rear
main bearing journal is hollow and is fitted with a screwed-in plug
at the front, and a pressed-in plug at the rear. The crankshaft gear
is secured to the end of the rear main bearing journal by cap screws.
(4) Dynamic Damper. The dynamic damper is mounted to the
rear crankshaft section. The damper consists of a steel counterweight
hung on an extension of the rear crankcheek by two loose fitting pins.
The loose fit permits a limited travel of the weight with reference to
the crankcheek extension. The ends of the pins are flanged so that
they can be removed from the pin holes only when the pin holes line
up with the crankcheek extension holes. A steel stop plate bolted
to the crankcheek extension prevents the holes from Fining up except
during disassembly.
j. Accessory Drive Mechanism (fig. 9).
( 1 ) Crankshaft Gear. Engine accessories such as the generator,
tachometer, fuel pump, magnetos, oil pump, etc., are driven through
a train of gears by the crankshaft gear. The crankshaft gear is
attached to the rear end of the crankshaft and is housed between
the diffuser and main crankcase sections (fig. 210). The gear in-
corporates a flexible spring drive which provides a cushion effect to
protect the accessories and the impeller from acceleration load.
(2) Starter Drive Gear. The crankshaft gear meshes directly
with the starter drive gear (fig. 9). The starter gear is the upper of
the two gears driven by the crankshaft gear. The starter drive gear
is splined on the starter shaft which extends through the diffuser to
the rear crankcase section and also carries the starter shaft gear at
the rear (fig. 185). The starter drive gear is retained on the starter
shaft by the starter shaft bolt which passes through the entire length
of the starter shaft and carries the cam driven pinion gear on its
forward end.
(3) Generator Idler Gear. The starter shaft gear (fig. 185)
meshes with the generator idler gear (fig. 177). This gear is mounted
on the generator idler gear shaft in the rear crankcase section. The
generator idler gear, in turn, meshes with the generator intermediate
16
STARTER DRIVE
GEAR
NE DESCRIPTION AND DATA
Figure 9 — Accessory Drive Mechanism
TM 9-1725
3
ORDNANCE MAINTENANCE - ORDNANCE ENGINE
MODEL R975-C4 (CONTINENTAL)
ELBOW ATTACHING CLAMPING DISTRIBUTOR BLOCK
NUTS— v SCREW , COVER-,
Figure 10 — Magneto Installed
gear which meshes with the generator drive gear and operates the
generator.
(4) Accessory Drive Gears. The starter drive gear meshes with
two accessory idler gears which, in turn, mesh with and drive two
accessory drive gears (fig. 9). These drive gears are keyed to the
forward ends of the accessory drive shafts which extend through the
diffuser to the rear crankcase section,
(5) Right Accessory Drive Shaft. A gear integral with the
right accessory drive shaft operates the tachometer and three-way
accessory drive. The tachometer and three-way accessory drive, in
turn, drives the tachometer drive and the three-way accessory drive.
The gear at the forward end of the tachometer and three-way acces-
sory drive operates the tachometer drive. The gear at the rear end of
18
-TERMINAL NUT COVER
CONDUIT ELBOW
RA PD 314685
Figure 11 — Fuel Pump Mounted
the tachometer and three-way accessory drive operates the three-way
drive which, in turn, operates the fuel pump. Two additional openings
in the three-way housing are available for driving other accessories.
The right magneto is also driven by the right accessory drive shaft.
The magneto drive gear is splined to a coupling attached to the rear
end of the accessory drive shaft.
(6) Left Accessory Drive Shaft. A gear integral with the left
accessory drive shaft operates the oil pump gear which drives the
oil pump drive shaft and operates the oil pump mounted to the rear
crankcase section. The left magneto is also driven by the left
accessory drive shaft. The magneto drive gear is splined to a coupling
at the rear end of the accessory drive shaft.
(7) Impeller Drive Gear. The crankshaft gear (subpar. (1),
above) also drives the impeller drive gear (fig. 9) through the medium
of the smaller gear of a pair supported by an intermediate shaft
bracketed to the front wall of the diffuser section. As the smaller
gear turns the shaft, it causes the impeller drive gear to turn. This
gear meshes with the impeller shaft gear to drive the impeller.
TM 9-1725
3
ENGINE
FUEL PUMP TO
-CARBURETOR LINE
DESCRIPTION AND
GOVERNOR
DRAIN LINE
DATA
-DRAIN LINE TO SUMP
19
TM 9-1725
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ORDNANCE MAINTENANCE - ORDNANCE ENGINE
MODEL R975-C4 (CONTINENTAL)
k. Ignition System.
(1) General. This system provides the ignition which fires the
spark plugs and ignites the fuel mixture in each cylinder. The
ignition system consists of the ignition harness (fig. 192), and mag-
netos (fig. 3).
(2) Ignition Harness (fig. 192). A shielded harness attached to
the outside of the main crankcase section carries rubber-insulated
ignition wires to the base of each cylinder. Individual shielded con-
duits carry the wires from the shielded harness to the shielded spark
plugs.
(3) Magnetos. Ignition is furnished by two magnetos mounted
on the rear crankcase section (fig. 10). The right-hand magneto fires
the front spark plugs; the left-hand, the rear spark plugs. The
magnetos turn at 1 Vs crankshaft speed.
l. Fuel System.
(1) General. The principal parts of the fuel system are the fuel
pump, carburetor, air horn, governor and throttle box, diffuser sec-
tion, and induction tubes. Fuel for operating the engine is pumped
from the fuel tank to the carburetor where it is mixed with air drawn
in through the engine breathers and air horn. The fuel mixture is
IDLE MIXTURE
ADJUSTMENT
CARBURETOR-TO-THROTTLE
BOX NUTS-
DEGASSER'
UNIT
AIR INLET
OPENING-
-FLOAT BOWL DRAIN PLUG-
Figure 1 2 — Carburetor Mounted
AIR INLET
OPENING
RA PD 314633
20
TM 9-1725
3
ENGINE DESCRIPTION AND DATA
NUTS (LOWER) BRACKET RA PD 314635
Figure 1 3 — Governor and Throttle Box
drawn by suction from the carburetor through the throttle box and
governor (which controls the flow of the fuel mixture), through the
carburetor elbow and rear crankcase section to the impeller. The
impeller picks up the mixture and forces it through the directional
vanes of the diffuser section to the distribution chamber. From here
the mixture is forced under pressure, through induction tubes, into
the cylinders and combustion chambers.
(2) Fuel Pump. The fuel pump is mounted by means of an
adapter attached to the three-way mounting pad on the accessory
housing (fig. 11). The fuel pump is of the diaphragm type and con-
trols the pressure of the fuel delivered to the carburetor. The pump
is operated through a train of gears driven by the crankshaft gear.
(3) Carburetor. The carburetor is of the single, Venturi type
mounted to an adapter elbow attached to the rear crankcase section
and supported by a carburetor support bracket (fig. 13). The car-
buretor is fed from a single float chamber, incorporates a needle-type
mixture control, and has an automatic fuel shut-off. The carburetor
is also equipped with a built-in degasser which shuts off the flow of
gas when the engine is decelerated quickly.
(4) Air Horn. Air is inducted into the carburetor through
breathers and an air horn. The breathers are air intakes in the
vehicle itself. The air horn is bolted to the bottom of the carburetor
21
TM 9-1725
3
ORDNANCE MAINTENANCE - ORDNANCE ENGINE
MODEL R975-C4 (CONTINENTAL)
MOUNTING FLANGE LFLAME ARRESTER RA PD 314694
Figure 14 — Fuel Induction Tube
by four cap screws (fig. 12), and feeds air into the bottom of the
carburetor. A suction line, between the carburetor throttle body and
bottom of the air horn, picks up any raw gasoline which might
accumulate in the air horn.
(5) Governor and Throttle Box. The governor is mounted
on the oil pump accessory drive mounting pad; the throttle box to
the carburetor adapter elbow (fig. 13). The governor is connected
to the throttle box by linkage from the governor control arm to the
throttle box valve arm (fig. 13). The governor is regulated to control
the flow of fuel from the throttle box to prevent over-speeding the
engine. It is of the fly-ball type and is driven at engine speeds. As
the engine speed increases, the centrifugal force of the weights over-
comes the tension of a spring, closing the valve in the throttle box.
If engine revolutions per minute are below the set speed, spring tension
overcomes the force of the flyweights, allowing the valve in the
throttle box' to open, thus increasing fuel flow to the engine and
increasing engine speed.
(6) Diffuser Assembly. The diffuser, or impeller mechanism,
speeds the delivery of the fuel mixture under pressure to the engine
cylinders. The mechanism consists of the impeller, diffuser ring, and
the diffuser and distribution chambers (fig. 158).
(7) Fuel Induction Tubes. Fuel induction tubes are made of
seamless steel tubing (fig. 14) and are joined to the distribution
chamber by means of a rubber seal and gland nut. The flanged end
of each tube is secured to the, cylinder head, at the intake port, by t
three cap screws. A flame arrestor designed to prevent backfire
flames from entering the distribution chamber is incorporated into
each fuel induction tube (fig. 14).
m. Engine Lubrication System.
(1) General. All moving contact surfaces of the engine, except
ball and roller bearings, are lubricated by a pressure oil system. Ball
and roller bearings are lubricated by splash.
22
TM 9-1725
3
ENGINE DESCRIPTION AND DATA
23
TM 9-1725
3
ORDNANCE MAINTENANCE - ORDNANCE ENGINE
MODEL R975-C4 (CONTINENTAL)
(2) Oil Pump (fig. 184). Pressure feed, dry sump engines such
as the R975-C4, require at least two oil pumps. One delivers oil to
the engine, the other removes oil from the engine sump and returns it
to the oil supply tank. Both oil pumps are combined in a single unit.
Oil is pumped in by the pressure pump section and delivered to the
engine at a pressure controlled by the adjustable relief valve. After
the oil has performed its lubricating functions, it drains to a small
sump at a low point in the crankcase. The scavenger pump section
of the pump removes oil from the sump through a passage in the rear
case. The capacity of the scavenger section of the pump is approxi-
mately 25 percent greater than the pressure pump. This assures re-
moval of oil from the sump as fast as it accumulates. The outlet of
the scavenger section of the pump delivers the oil back to the oil sup-
ply tank.
(3) Main Pressure Passage. Oil is drawn from the external oil
tank through an oil strainer in the oil pump and is forced under pres-
sure into a passage in the crankcase rear section. This passage is the
main supply for all oil pressure lines and is called the main pressure
passage (fig. 15).
(4) First Main Oil Pressure Line (fig. 15).
(a) Valve Mechanism. Oil flows under pressure from the main
pressure passage through a drilled hole to the main crankcase section.
This hole terminates in an annular passage which runs completely
around the main crankcase section. The hole through to the annular
passage is known as the first main oil pressure line (fig. 15). Oil is
forced from the annular passage to the valve tappet guides. When
valve tappet oilholes index the guide holes, lubrication is forced into
the tappets, through the push rod sockets and hollow push rods, to
the rocker arms and rocker arm bearings, in the rocker boxes. Excess
oil in the rocker boxes drains through oil drain pipes connected to the
rocker boxes, and through the push rod housings and crankcase to the
oil sump.
(b) Camshaft Assembly. Oil from the first main oil pressure
line (fig. 15) also passes through a pressed-in tube in the main crank-
case section to an annular groove in the crankshaft rear main bearing
support. Oil flows under pressure from this groove, through drilled
passages to the rear main bearing, and on into the hollow bearing
journal from which a drilled hole conducts it to the hollow crankpin.
Oil passes through the crankpin holes to the master rod bearing, and
thence to the knuckle pins and knuckle pin bushings. Any excess oil
on the knuckle pins is thrown off the pins and helps to splash-lubricate
the cylinder walls, pistons, and piston pins. Cylinder walls, pistons,
and piston pins are also lubricated by oil which flows through a spray
hole in the rear end of the crankpin.
24
TM 9-1725
3
ENGINE DESCRIPTION AND DATA
Figure 16 — Oil Scavenger System
(c) Cam Assembly. Oil flows from the annular groove in the
crankshaft rear main bearing support, through a groove in the cam
hub bearing support, and lubricates the cam hub bearing. Oil from
the cam and cam hub bearing helps to oil the valve tappets and valve
tappet guides.
(d) Front Main and Thrust Bearings. These bearings receive
a sufficient amount of lubrication by splash. Oil from the main crank-
case section lubricates the main bearing, and oil passing through the
bearing into the front crankcase section lubricates the thrust bearing.
(5). Second Main Oil Pressure Line.
(a) General. The second main oil pressure line consists of a hole
drilled from the first main oil line to the left accessory shaft bushing
and through the length of the accessory shaft (fig. 15). Oil flowing
25
TM 9-1725
3
ORDNANCE MAINTENANCE - ORDNANCE ENGINE
MODEL R975-C4 (CONTINENTAL)
under pressure from the main pressure passage, through the second,
main oil pressure line, lubricates the accessory drive mechanism in the
diffuser section, and two gear bushings in the rear crankcase section.
( b ) Left Accessory Drive Gear Bushing. From the second main
oil pressure line (fig. 15), oil flows under pressure through two
holes in the forward part of the left accessory drive shaft, and fills
an annular groove on the outside diameter of the shaft. The oil
lubricates the shaft front bushing and passes into a drilled hole in
the diffuser section casting.
(c) Accessory Drive Mechanism. The hole in the diffuser section
conducts oil to a groove parallel with the circumference of the im-
peller shaft hole in the diffuser section. The groove is sealed at as-
sembly by the impeller shaft bearing support, and supplies oil through
radially drilled passages in the diffuser section casting, to the acces-
sory drive idler gears, impeller drive gear bushings, starter shaft, and
the right accessory drive shaft.
( d ) Right Accessory Drive Shaft Bushings. Oil flows from one of
the radially drilled passages in the diffuser section casting to the right
accessory drive bushing in the diffuser section. An annular groove
within the bushing conducts the oil to a hole in the right accessory
drive shaft. This hole is similar to the hole in the left accessory
drive shaft. Oil flows the length of the shaft to lubricate the right
accessory drive shaft bushing in the rear crankcase section.
(e) Starter Shaft Rear Bushing. Oil flows from another of the
radially drilled passages in the diffuser section casting to an annular
recess formed between the starter shaft forward bushing and the
starter shaft. From this recess, the oil passes through the starter
shaft rear bushing and through a longitudinal groove at the top of
the bushing, lubricating the starter shaft rear bushing. Oil escaping
from the bushing lubricates the generator, idler, and drive gears by
splash. .
(6) Third Main Oil Pressure Line.
(a) General. The third main oil pressure line consists of a hole
drilled directly across the rear main crankcase section casting
(fig. 15). Two outlets lead from this line. One leads to an annular
groove on the outside diameter of the generator drive gear support.
The other leads down to the generator support pad. Oil flowing under
pressure from the main pressure passage through the third main oil
pressure line lubricates the accessory drive mechanisms in the rear
crankcase section.
(b) Generator Idler Gear Shaft and Bushing. Oil flows through
a drilled passage in the generator idler gear shaft which cuts into the
main pressure passage. It flows out of a hole drilled in the forward
part of the shaft to lubricate the generator idler gear shaft and bushing.
26
TM 9-1725
3-4
ENGINE DESCRIPTION AND DATA V -
(c) Generator Drive Gear Shalt and Bushing. Oil flows from the
third main oil pressure line (fig. 15) through a drilled hole in the
rear crankcase casting, which conducts the oil to the generator drive
gear support. One of two holes in the support leads the oil to the
generator drive gear shaft and bushing.
(d ) Tachometer and Fuel Pump Drive Gear Shalt and Bushings.
A second hole drilled through the generator drive gear support con-
ducts lubrication to another drilled passage leading to the tachometer
and fuel pump adapter. The oil lubricates the tachometer and fuel
pump drive gear shaft and bushing.
(7) Oil Scavenger System (fig. 16). Oil drains into the main
crankcase section from the other crankcase sections through indexing
holes and slots, and to the sump fitting in the rear bottom of the main
crankcase section. Oil in the front crankcase section drains to the
sump fitting in the forward bottom part of the main crankcase
section. The oil is picked up from the sump fitting by the scavenger
section of the oil pump and drawn through a passage, which runs
through the main, diffuser, and rear crankcase sections. The pump
forces thg oil back to the oil supply reservoir in the vehicle. Oil
which has drained down to the sump tanks is drawn up through tubes
to the sump fittings.
4. DATA.
a. General.
Make
Model
Type
Number of cylinders
Bore and stroke
Piston displacement
Compression ratio
^ Rated bhp
Governed speed
Crankshaft rotation (from rear)
Crankshaft spline size
Mounting bracket:
Diameter of circle
Number of bolts
Size of bolts
Dry weight of engine (basic) . .
b. Valves.
Timing
Intake opens
Intake closes
Continental
R975-C4
Single-row, static-radial,
air-cooled
9
5.00 x 5.50
973 cu in.
5.7 to 1
.... 485 @ 2,400 rpm
2,300 rpm
Clockwise
S.A.E. No. 30
23% in.
9
fe in -
750 lb
(set at 0.070 in. cold)
8° B.T.C.
34° A.B.C.
27
TM 9-1725
4
ORDNANCE MAINTENANCE - ORDNANCE ENGINE
MODEL R975-C4 (CONTINENTAL)
Exhaust opens 56° B.B.C. (+ or -4°)
Exhaust closes 19° A.T.C.
Valve clearance, service 0.006 in., cold
c. Cylinder Temperatures.
Cylinder head temperature
Normal maximum 450° F.
Maximum, for short periods . . . . - 500° F.
Cylinder barrel temperature, maximum 350° F.
d. Ignition.
(1) Magnetos.
Make ' Scintilla
Type VAG9DFA
Rotation Counterclockwise
Speed 1.125 to 1
Firing position, right magneto at full advance fires at .... 29° B.T.C.
Firing position, left magneto at full advance fires at 26° B.T.C.
(2) Sparkplugs Champion 63S
(3) Generator.
Make Bendix-Eclipse
Model 31
(4) Starter.
Make Delco-Remy
Model 1108685
(5) Booster Coil.
Make Delco-Remy
Model 1115482
Make Auto-Lite
Model BC-400
e. Fuel System.
(1) Carburetor
Make
Model
(2) Fuel Pump.
Make
Model
(3) Governor
Make
Model
(4) Primer.
Make
Priming system connections
(5) Fuel Specification.
Octane rating
Stromberg
NA-R9G
AC
GP-11972
Pierce
Mal522
CMC
Vs-in. standard pipe
U. S. Army 2-103A
80
28
TM 9-1725
4
ENGINE DESCRIPTION AND DATA
Fuel pressure 3 Vi to 5 lb
Carburetor connection Vz -in. standard pipe
f. Lubrication System.
Oil pump , Continental
■=-' Oil consumption, @ rated power 0.025 lb per bhp per hr
Oil inlet and outlet connections 3 A- in. standard pipe
Oil flow . 14-22 lb/min/
Oil pressure @ 2,400 rpm 75 lb + or — 5 lb
Oil pressure at idling speed (800 rpm) 35 lb -f- or — 5 lb
Oil specification:
Viscosity, above 32° F S.A.E. 50
Viscosity, below 32° F S.A.E. 30
29
TM 9-1725
5
ORDNANCE MAINTENANCE - ORDNANCE ENGINE
MODEL R975-C4 (CONTINENTAL)
n I IT/-U Tl I n/-\l i l ^\l IT nc* nui/' I IT/-l ■ nni-Cf«linr m > -pi-
Figure J 7 — Removing Clutch Spindle Flange Retaining Nut
CHAPTER 3
DISASSEMBLY OF ENGINE INTO SUBASSEMBLIES
Paragraph
Preliminary instructions 5
Clutch, flywheel, and fan removal 6
Accessories, removal 7
Engine supports, collector ring, and cowling, removal 8
Front and main crankcase sections, removal 9
Rear crankcase and diffuser sections, removal 10
5. PRELIMINARY INSTRUCTIONS.
a. Mount Engine on Stand. Install engine on a suitable rotating
mounting stand.
b. Clean Exterior of Engine. Plug all openings to interior of
engine. Remove all dirt and grease from exterior of engine with dry-
cleaning solvent or with steam. Do not steam-clean engine except just
before disassembly as remaining steam condensation might cause rust.
30
CLUTCH PRESSURE PLATE
OPENINGS IN COWLING—'' 3/4-IN. BOX WRENCH-' RA PD 314627
Figure 19 — Removing Clutch Pressure Plate Retaining Nuts
TM 9-1725
5
DISASSEMBLY OF ENGINE INTO SUBASSEMBLIES
RA PD 314768
Figure 18 — Removing Clutch Spindle Flange
WOOD BLOCKS
3/4-IN. SOCKET
TM 9-1725
5-6
ORDNANCE MAINTENANCE - ORDNANCE ENGINE
MODEL R975-C4 (CONTINENTAL)
Figure 20 — Removing Flywheel Ring and Clutch Pressure Plate
As subassemblies are removed from engine, place them on a wooden,
or composition top inspection bench covered with paper to prevent
possible damage to engine parts.
6. CLUTCH, FLYWHEEL, AND FAN REMOVAL.
a. Remove Clutch Spindle Flange. Pull cotter pin from flange
retaining nut, and remove nut (fig. 17), using wrench (41-W-3058-
300). Pull flange straight off clutch spindle (fig. 18). If neces-
sary, use a standard bearing puller to remove flange.
h. Remove Flywheel Ring and Pressure Plate. With screw-
driver,, loosen six Dzus fasteners from each of four covers attached to
engine cowling (fig. 19). Remove four covers. Insert two snug fit-
ting wood blocks between clutch throw-out bearing flange and face
of pressure plate. Reach through cover openings, one at a time, with
%-inch wrench and hold bolt heads (fig. 19). Loosen 12 nuts on bolts
which hold flywheel ring and pressure plate to flywheel. Remove
nuts. Install jack screws through three holes in flywheel ring. Turn
32
Figure 2 1 — Removing Cotter Pin from Front Cone Nut
Retaining Pin
screws in to separate flywheel ring and pressure plate from flywheel.
Lift flywheel ring and pressure plate assembly from engine (fig. 20).
The clutch spindle, driven disks, and drive plate, may come out with
the pressure plate assembly, so handle carefully to prevent damaging
any of these parts.
c. Remove Clutch Parts. If these parts did not come out with
the pressure plate, remove clutch outer driven disk. Prick-punch
clutch drive plate and flywheel to insure alinement during reassembly
(fig. 251). Remove drive plate, inner driven disk, and clutch spindle.
d. Remove Flywheel and Fan Assembly. Remove cotter pin
from the retaining pin which locks the front cone nut on crankshaft,
and remove washer and retaining pin (fig. 21). Insert bar through
holes in front cone nut; loosen and remove nut (fig. 22) and split cone.
Using a lifting eye (fig. 23), or with the help of another person, lift
or slide flywheel and fan assembly off crankshaft splines (fig. 24).
Screw protector cap on threads at end of crankshaft.
33
TM 9-1725
6-7
ORDNANCE MAINTENANCE - ORDNANCE ENGINE
MODEL R975-C4 (CONTINENTAL)
Figure 22 — Removing Flywheel Front Cone Nut
7. ACCESSORIES, REMOVAL.
a. Remove Fuel and Drain Lines. Start at rear of engine. Loosen
clamps at both ends of hose connecting fuel pump and carburetor.
Remove hose (fig. 11). Disconnect fittings at each end of drain line
running from governor to fuel pump adapter elbow. Remove drain
line (fig. 11). Disconnect fittings at each end of drain line running
from fuel pump adapter elbow to sump. Remove drain line (fig. 11).
I). Remove Conduit at Carburetor. Loosen elbow nut on con-
duit elbow, and pull conduit back. Unscrew and remove upper cap
from degasser unit (fig. 11). Remove nut, lock washer, and plain
washer which secure wire terminal to terminal post. Remove ter-
minal from post. Pull out wire. Remove clip holding conduit to rear
engine support and slip conduit off wire (fig. 11). CAUTION: Rein-
34
RA PD 314695
Figure 23 — Removing Flywheel and Fan Assembly with
Lifting Bye
stall plain washer, lock washer, and nut on terminal post. Replace
upper cap on degasser unit so that these will remain with carburetor
assembly.
c. Remove Fuel Pump. Cut and remove safety wires. Remove
four nuts and washers from studs which hold fuel pump adapter elbow
to mounting pad for three-way accessory drive housing (fig. 25). Re-
move fuel pump and elbow from engine as an assembly. Pull fuel
pump drive gear from square adapter on drive gear shaft, to elimi-
nate the possibility of the gear falling out and being damaged.
d. Remove Carburetor. Cut and remove lock wire from carbu-
retor attaching nuts. Support carburetor adequately, and remove
four nuts, and flat washers from bolts holding carburetor to throttle
box (fig. 12). Remove carburetor and composition gasket.
e. Remove Carburetor Support Bracket. Cut and remove
safety wires from two cap screws holding carburetor support bracket
to each side of rear crankcase section (fig. 13). Remove cap screws
and washers. Remove bracket and composition gasket from throttle
box.
35
TM 9-1725
7
ORDNANCE MAINTENANCE - ORDNANCE ENGINE
MODEL R975-C4 (CONTINENTAL)
Figure 24 — Removing Flywheel and Fan Assembly
f. Remove Throttle Box. Remove cotter pin from lower clevis
pin of linkage connecting governor and throttle box. Pull out clevis
pin and remove washer (fig. 26). Cut and remove safety wires. Re-
move four nuts and washers from studs which secure throttle box to
carburetor elbow. Lower throttle box and gasket, and remove from
studs on carburetor elbow.
g. Remove Magneto Shielding. Cut both magneto ground wires
and the primary booster coil wire as close to loose terminal ends as
possible (fig. 3). Unscrew nut attaching shielding to left magneto
outer elbow (fig. 27). Remove shielding from over three cut wires.
Coil left magneto ground wire, and attach coil to left magneto elbow.
Unscrew nuts attaching inner elbow shielding to both magnetos
(fig. 27). Pull right magneto ground wire and primary booster coil
36
TM 9-1725
7
DISASSEMBLY OF ENGINE INTO SUBASSEMBLIES
THREE-WAY DRIVE HOUSING
MOUNTING NUTS
SHIELDINGS AND CABLES
TO IGNITION HARNESS-
TM 9-1725
7
ORDNANCE MAINTENANCE - ORDNANCE ENGINE
MODEL R975-C4 (CONTINENTAL)
38
Figure 27 — Magneto and Booster Coil Shielding
TM 9-1725
7
DISASSEMBLY OF ENGINE INTO SUBASSEMBLIES
BOOSTER COIL -> SHIELDING FOR SECONDARY WIRE R A PD 314637
Figure 28 — Booster Coil
wire through left magneto elbow. Remove inner elbow shielding.
Coil right magneto ground wire and attach coil to right magneto elbow.
Unscrew nut attaching shielding for primary booster coil wire to right
magneto outer elbow (fig. 27), and knurled nut attaching shielding to
booster coil (fig. 28). Pull primary wire through right magneto elbow
and remove shielding. Coil primary wire and attach to booster coil.
h. Remove Booster Coil. Unscrew nut holding shielding for sec-
ondary booster coil wire to booster coil (fig. 28). Disconnect shield-
ing elbow from coil, by unscrewing elbow hexagonal nut and pulling
out elbow and cigarette connector. Remove connector from end of
secondary wire. Unscrew nut attaching shielding for secondary wire
to front of right magneto elbow (fig. 27). Slide off shielding. Coil
secondary wire, and attach coil to right magneto elbow. Remove two
fillister-head screws holding booster coil to engine support. Remove
screws and toothed lock washers; remove coil (fig. 28).
i. Remove Starter. Remove cotter pins from eight nuts which
39
TM 9-1725
7
ORDNANCE MAINTENANCE - ORDNANCE ENGINE
MODEL R975-C4 (CONTINENTAL)
STARTER v ATTACHING NUTS AND BOLTS -
GENERATOR
SUPPORT PLATE
RA PD 314663
Figure 29 — Starter-generator Support Plates
hold starter-generator support bracket side plates to support bands
(fig. 29). Remove the nuts, washers, and bolts; then remove side
plates. Cut and remove safety wires from six hold-down nuts which
hold starter on mounting studs. Remove nuts (fig. 30) using wrench
(41-W-871-45), and supporting starter. Remove plain washers and
lift off starter. Install cover plate over starter opening, and secure it
in place with two or three hold-down nuts turned fingertight.
j. Remove Magneto Distributor Block Covers. Remove two cap
screws, lock washers, and flat washers, holding conduit elbow to top
of each magneto distributor block cover (fig. 30). Remove safety
pins from cover locking clamps on each side of each magneto (fig. 10).
Push clamps on side of each cover in and down to release cover.
Remove two nuts, lock washers, and bolts that clamp the two halves
of each distributor block cover together. Lift cover halves from each
magneto.
40
TM 9-1725
7
DISASSEMBLY OF ENGINE INTO SUBASSEMBLIES
BLOCK COVER RA PD 314659
Figure 30 — Removing Starter Attaching Nuts
k. Remove Magnetos. Pull magneto distributor blocks out at top
and lift from magnetos. Slide up rubber grommet from both mag-
netos, and disconnect secondary booster coil wire from right magneto.
Disconnect ground wire from both magnetos. Cut and remove safety
wires. Remove three nuts and flat washers which secure each mag-
neto to rear of crankcase (fig. 10). Remove both magnetos.
l. Remove Generator. Cut and remove safety wires from four
nuts securing generator to generator support pad. Remove four nuts
(fig. 32), using wrench (41W-636-550). Remove washers from
studs and pull generator from generator support pad. Remove gas-
ket from generator support pad.
m. Remove Generator Support Pad. Try to work support pad
off studs and dowel. If support cannot be worked off, use a flat pry
bar. CAUTION: Keep gasket between bar and face of generator
support pad to prevent damaging the pad when prying. Lift support
pad off gasket crankcase studs and dowel. Remove gasket. Install
cover on generator opening. Secure cover with two nuts tightened
fingertight.
n. Remove Governor. Remove four palnuts, plain nuts, and
washers holding governor to oil pump. Pull governor straight off oil
41
TM 9-1725
7-8
ORDNANCE MAINTENANCE - ORDNANCE ENGINE
MODEL R975-C4 (CONTINENTAL)
CONDUIT ELBOW
DISTRIBUTOR
BLOCK
MOUNTING NUT
RIGHT-HAND
MAGNETO
RA PD 314651
Figure 3 1 — Magneto Conduit Elbow Removed
pump studs. Install cover on opening and secure in place with two
nuts tightened fingertight. Figure 34 shows engine with accessories
removed and opening covers installed.
8. ENGINE SUPPORTS, COLLECTOR RING, AND COWLING,
REMOVAL.
a. Suspend Engine from Sling. Attach engine sling to rocker
arm hub bolt nuts. Remove four nuts and bolts which secure each
end of rear engine support to engine mounting stand (fig. 34). Lift
engine straight up until both front and rear supports clear engine
mounting stand.
b. Remove Engine Rear Support. Remove cotter pins from
nine engine support ring nuts (fig. 34). Remove nuts, washers, and
42
TM 9-1725
8
DISASSEMBLY OF ENGINE INTO SUBASSEMBLIES
Figure 32 — Removing Generator
bolts, at nine points around support ring to disconnect support from
engine. Engine is now suspended from sling.
c. Remove Exhaust Collector Ring. Cut and remove safety wires
from two nuts which secure collector ring segments to studs on each
cylinder exhaust elbow. Remove nuts, and washers. There are 10
nuts for the left ring segment and 8 for the right. Remove exhaust
collector ring segments from exhaust elbows as assemblies (fig. 35).
Remove and discard copper gaskets at exhaust elbows. Lower engine
to disassembly stand. Fasten engine to stand and remove sling.
d. Remove Engine Front Support Bar. Cut and remove safety
wires from 10 stud nuts on support bar center clamp at front of engine
(fig. 36). Loosen nuts on studs and slide bar out from either side of
clamp.
e. Remove Cowling. Loosen three Dzus fasteners which secure
each of the nine cylinder head baffles to engine cowling (fig. 37).
43
SUPPORT
ATTACHING BOLTS
RA PD 314646
Figure 34 — Engine Rear Support Attachment
44
CARBURETOR
ELBOW
LEFT HAND
EXHAUST RING
L RIGHT HAND
EXHAUST RING
RA PD 314647
Figure 35 — Exhaust Collector Ring
Loosen the fasteners by turning them counterclockwise V 2 turn. The
cowling is now disconnected from the baffles. Loosen two Dzus fas-
teners which secure each intercylinder baffle to cowling (fig. 37).
Spring baffles outward to release fasteners from cowling. Remove
cotter pins from seven nuts on bolts securing cowling to engine. Re-
move nuts, flat washers, and bolts. Raise cowling straight up off
engine.
f. Drain Oil. With engine in upright position, drain oil from engine
by taking plug out of drain housing located between the sump tanks
(fig. 39).
9. FRONT AND MAIN CRANKCASE SECTIONS, REMOVAL,
a. Remove Sump Assembly.
(1) Remove Tank Assembly. Loosen six hose clamps which
TM 9-1725
9
ORDNANCE MAINTENANCE - ORDNANCE ENGINE
MODEL R975-C4 (CONTINENTAL)
CDi^klT rDAkll/rACC CC/~TI/^kl
SUPPORT BAR J ZL_ CLAMPING NUTS RA PD 314662
Figure 36 — Engine Front Support Bar and Mounting Clamp
secure three connecting hose running from connecting pipes between
sump tanks and main sump fitting in bottom of main crankcase sec-
tion (fig. 39). Remove cotter pins, nuts, bolts and spacing washers
that hold sump tanks to rear of rocker boxes on the No. 5 and No. 6
cylinders. Cut and remove safety wires. Take off two nuts which
hold each sump tank to drain tubes located between the cylinders.
Remove nut and washer, from studs which hold each sump tank to
cylinder heads. Lift off sump tanks.
(2) Remove Sump Spider. Cut safety wire, and remove two cap
screws and flat washers which hold drain tube running from front of
the main crankcase section to spider assembly (fig.' 38). Pull drain
tube forward from between the baffles and remove. Unscrew cap and
remove washer from bottom of spider assembly. Slide spider assem-
bly from fitting in bottom of main crankcase section.
b. Remove Front Spark Plugs. Elbow connectors are located at
the spark plug end of each ignition wire front conduit. Loosen lock-
ing nut at spark plug end of each elbow connector, and pull cigarette
connector out of each spark plug. Cover each cigarette connector
immediately with suitable protector (fig. 40). Remove spark plugs
from cylinders, using 1-inch deep socket wrench.
c. Disconnect Baffle Attaching Springs. Pull hooked end of in-
46
TM 9-1725
9
RA PD 314656
Figure 37 — Engine Cowling Attachments
tercylinder baffle attaching spring out over attaching bracket, and
disconnect spring from bracket (fig. 41). Spring remains attached to
baffle. Lift bracket out from between cylinders (fig. 42). Perform
this operation for each of nine intercylinder baffles.
d. Remove Primer System. Loosen connecting nut that holds
each primer system line to cylinder head. Loosen clamp nuts, and
remove clamps that hold each primer line to the fuel induction tube.
Cut and remove safety wires. Remove two screws and washers which
hold distributor assembly for primer system to No. 1 induction tube
(fig. 43). Remove primer system from engine as an assembly.
e. Remove Crankcase Breather. Loosen four hose clamps on
hose which connect breather to front and rear crankcase sections
(fig. 44). Remove two nuts, flat washers, and bolts which secure
breather to rocker boxes on the No. 1 cylinder. Remove breather
from engine.
DISASSEMBLY OF ENGINE INTO SUBASSEMBLIES
-DZUS FASTENERS , CYLINDER HEAD BAFFLE
sf-
COWLING ATTACHING BOLT AND NUT
47
TM 9-1725
9
ORDNANCE MAINTENANCE - ORDNANCE ENGINE
MODEL R975-C4 (CONTINENTAL)
Figure 38 — Sump Drain Tube Connection at Main
Crankcase Section
f. Remove Rocker Box Covers. Remove four stud nuts, lock
washers, and flat washers that hold each rocker box cover to rocker
box (fig. 4). Lift cover and gasket from studs on rocker box. Where
two covers are connected together by a drain tube, remove both covers
at the same time. Do not disconnect rubber drain tube unless it needs
to be replaced. If design of engine mounting stand permits, turn
engine around so that all oil will be drained from each rocker box.
g. Remove Rocker Arm Assemblies. Make sure valve being
worked on is in closed position, or rotate crankshaft with timing bar
(par. 73 m), until valve is in closed position. Break loose all rocker
arm adjusting screw lock nuts (fig. 45). Pull cotter pin from rocker
arm hub bolt nut. Holding bolt head (fig. 46), remove nut and
washer. Slide bolt and washer from rocker box. Lift out rocker arm
assembly. Remove other rocker arm assemblies in same way.
h. Remove Push Rods and Housings. Push rods are free after
rocker arms are removed. Lift push rods out of push rod housings
which connect each rocker box to a push rod adapter in the main
crankcase (fig. 47). Each housing is attached to its rocker box and
adapter by two hose and three clamps. Loosen hose clamp nearest
the rocker box, using wrench (41-W-1986); then loosen hose clamp
nearest crankcase. Slide the clamp and hose nearest rocker box away
48
2. Front View Sump and Tanks RA PD 314774
Figure 39 — Oil Sump
49
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ORDNANCE MAINTENANCE - ORDNANCE ENGINE
MODEL R975-C4 (CONTINENTAL)
PROTECTOR
CIGARETTE CONNECTOR
RA PD 114660
Figure 40 — Installing Protector on Front Spark Plug
Cigarette Connector
from the box and over the push rod housing. Raise the end of the
housing nearest the rocker box and pull the housing assembly off the
push rod adapter. Remove all push rod housings in same way.
i. Remove Push Rod Sockets and Springs. Reach into the
crankcase opening with a piece of wire. Insert end of wire through
hole in push rod socket and spring, and pull them both out (fig. 49).
Remove socket and spring for each push rod in same way.
j. Remove Cylinder Head Baffles. Remove the cap screw, lock
washer, and flat washer that hold each cylinder head baffle to cylinder
head, and remove baffle (fig. 50). Remove all nine baffles in same
way. NOTE: The cap screw removed also serves as an attaching
screw for the fuel induction tube secured to cylinder head.
k. Remove Fuel Induction Tubes. Unscrew gland nut at inner
end of each fuel induction tube (fig. 51) using wrench (41-W-1537).
50
TM 9-1725
9
DISASSEMBLY OF ENGINE INTO SUBASSEMBLIES
SPRING
BRACKET
TM 9-1725
9
ORDNANCE MAINTENANCE - ORDNANCE ENGINE
MODEL R975-C4 (CONTINENTAL)
PRIMER LINES |— DISTRIBUTOR FOR PRIMER SYSTEM
No. 1 INDUCTION TUBE ' MOUNTING SCREWS
RA PD 314658
Figure 43 — Primer Distributor Bracket Mounted
Slide nut back on each tube. Loosen remaining two cap screws, lock
washers, and flat washers, holding each induction tube to cylinder
head (fig. 50). Pull tube out of recess in rear crankcase section.
Remove rubber seal from each recess and install seal on end of each
induction tube. Remove and discard induction tube flange gaskets.
l. Remove Rear Spark Plugs. Follow procedure outlined in sub-
paragraph 9 b, above. CAUTION: Be sure to install protectors on
spark plug cigarette connectors as soon as connectors are removed
from plugs.
m. Remove Intercylinder Baffle Assemblies. Lift up each baffle
assembly until it clears the cylinder exhaust elbow, and remove assem-
bly from between cylinders. Make sure that baffle retaining springs
do not catch on engine parts.
n. Loosen Starter Shaft Nut. Remove cover from starter open-
ing (par. 7 i). Insert cloth in opening under starter shaft to prevent
cotter pin or pieces of the cotter pin from dropping into rear crank-
case section. Pull cotter pin from starter shaft nut (fig. 52). Break
loose starter shaft nut. It is much easier to loosen starter shaft nut
at this time. Retighten nut fingertight. Remove cloth, and reinstall
starter cover. NOTE: This operation is necessary only when the
crankcase sections are to be separated.
o. Remove Cylinder and Piston Assemblies.
( 1 ) Remove Rear Cylinder Attaching Nuts. Cut and remove
52
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9
DISASSEMBLY OF ENGINE
INTO SUBASSEMBLIES
ATTACHING
BREATHER ASSEMBLY
BREATHER PASSAGE
HOSE CLAMPS
RA PD 314664
Figure 44 — Crankcase Breather Mounting
safety wires from eight attaching nuts on each cylinder. Remove four
attaching nuts from studs at rear of each cylinder (fig. 53) using a
special wrench supplied for this operation.
(2) Remove No. 2 Cylinder Assembly. Rotate engine crank-
shaft until No. 2 piston is at top center. Using same wrench, loosen
and remove four attaching nuts from studs in front of No. 2 cylinder.
Pull cylinder assembly from studs on cylinder mounting pads in main
crankcase section. CAUTION: Do not remove any other cylinder
assemblies at this time.
(3) Remove No. 2 Piston Assembly. Remove aluminum plugs
from both ends of No. 2 piston pin (fig. 54). Tap piston pin out of
piston with light hammer (fig. 55) using drift (41-D-1541-75.) and
supporting piston. Lift piston assembly from articulated connecting
53
Figure 46 — Removing Rocker Arm Hub Bolts
54
TM 9-1725
9
DISASSEMBLY OF ENGINE INTO SUBASSEMBLIES
PUSH RODS
3M
**A-\
«
PUSH ROD HOUSINGS -
RA PD 314644
Figure 48 — Loosening Push Rod Housing Clamp
rod, and install rod protector on cylinder hold-down studs (fig. 56).
If a rod protector is not available, use the cylinder lower oil seal.
(4) Remove Remaining Cylinder and Piston Assemblies.
Repeat the procedure outlined in subparagraphs (2) and (3) above,
TM 9-1725
9
ORDNANCE MAINTENANCE - ORDNANCE ENGINE
MODEL R975-C4 (CONTINENTAL)
Figure 49 — Removing Push Rod Socket and Spring
for the No. 3 cylinder, then for the No. 4, etc., until all cylinder assem-
blies have been removed. Install rod protectors for each rod as soon
as piston is removed. CAUTION: The No. 1 cylinder, in which the
master rod operates, must be removed last.
p. Remove Split Brass Cone. Remove protecting cap from
threaded end of crankshaft. Insert screwdriver in split brass cone
on shaft. Spread cone, and lift cone off shaft (fig. 58).
q. Remove Thrust Bearing Retaining Nut. Install special
wrench (4I-W-871-35) on thrust bearing retaining nut. Turn nut
off shaft while holding crankshaft stationary with timing bar, or
another suitable bar (fig. 59).
r. Remove Front Crankcase Section. Cut and remove safety
wires from 7 nuts holding front crankcase section cover to front
crankcase section (fig. 59). Remove nuts and fiat washers. Lift off
cover, laminated shim, and oil slinger (fig. 60). Cut and remove
safety wires from 28 nuts holding front crankcase section to center
section (fig. 60). Remove nuts and flat washers. Using a special
56
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9
DISASSEMBLY OF ENGINE INTO SUBASSEMBLIES
iwnnrTinw turf /uiniiMTiKir; rcpfwr
RA PD 314641
CYLINDER HE
Figure 50 — Removing Cylinder
5PANNER
INDUCTION TUBE
Figure 51 — Removing Fuel Induction Tube Gland Nut
57
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9
ORDNANCE MAINTENANCE - ORDNANCE ENGINE
MODEL R975-C4 (CONTINENTAL)
Figure 52 — Removing Cotter Pin from Starter Shaft Nut
puller supplied for this operation, remove front section (including
thrust bearing) from studs on main crankcase section (fig. 61).
s. Remove Front Main Bearing Support. Slide spool-like spacer
from crankshaft (fig. 62). Pull front main bearing support from studs
on main crankcase section (fig. 62), using three pullers (41-P-2906-
280), and exerting equal pressure on each. Lift front main bearing
outer race and roller assembly from inner race. Inner race remains
on crankshaft (fig. 63). Handle bearing with care to avoid loss of
rollers. Wrap bearing in oiled paper until ready to service or install.
Reinstall thread protector on end of crankshaft (fig. 63).
t. Remove Articulated Rods. Working through top (front) of
main crankcase section, bend down screw locks which secure articu-
lated rod knuckle pin locks (fig. 64). Turn crankshaft so that coun-
terweights are exactly opposite knuckle pins to be removed. Remove
two cap screws, screw locks, and knuckle pin locks. Insert threaded
end of puller (41-P-294 1-125) into knuckle pin (fig. 65). Install
58
ALUMINUM PLUG
No. 2 PISTON
RA PD 314650
Figure 54 — Removing Piston Pin Plug
59
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9
ORDNANCE MAINTENANCE - ORDNANCE ENGINE
MODEL R975-C4 (CONTINENTAL)
PROTECTORS FOR RODS RA PD 314693
Figure 56 — Connecting Rod Protector
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TM 9-1725
9
DISASSEMBLY OF ENGINE INTO SUBASSEMBLIES
MASTER ROD
RUBBER SEALS
RA PD 314674
Figure 58 — Removing Split Brass Cone from Crankshaft
bar, or ratchet, on puller. Hold head of puller (fig. 66) and master
rod in a fixed position. Turn puller. As knuckle pin clears master
rod flange (fig. 66), remove articulated rod. Repeat this operation
for each knuckle pin and articulated rod.
u. Remove Ignition Harness, Cut and remove safety wires from
four nuts that hold ignition harness bracket to studs on crankcase.
61
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ORDNANCE MAINTENANCE - ORDNANCE ENGINE
MODEL R975-C4 (CONTINENTAL)
Figure 60 — Removing Oil Slinger
Remove nuts (fig. 67), using a wrench. Unscrew knurled nut that
holds the two sections of the harness together (fig. 68). Lift harness
from engine, being careful not to catch ignition blocks on engine stand
as harness is removed.
v. Remove Main Crankcase Section.
(1) Remove by Lifting. Cut and remove safety wires from 16
remaining nuts that hold main crankcase section to rear section.
Remove nuts and flat washers. Lift main section, including crank-
shaft, from rear section studs (fig. 69).
62
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9
DISASSEMBLY OF ENGINE INTO SUBASSEMBLIES
RA PD 314676
Figure 61 — Removing Front Crankcase Section
(2) Remove with Lifting Eye. When using a lifting eye to
remove the main crankcase section, remove the front and main sec-
tions as an assembly and separate them later. Separating the sections
after removal prevents damage to the rear main bearing. After
removing cylinder assemblies (subpar. o above), remove ignition
harness and main section attaching nuts (subpars. u through v (1),
above). Attach lifting eye. Remove crankcase front and main
sections as an assembly (fig. 70). Proceed with disassembly steps
(subpars. p through t, above).
w. Remove Crankshaft Gear, Cut and remove lock wire from
eight square-headed cap screws (fig. 71). Remove cap screws, and
pull gear assembly from rear end of crankshaft.
x. Remove Crankshaft Assembly. Screw a nut onto each of the
four corner cylinder hold-down studs on the No. 9 cylinder pad to
protect the stud threads. Place main crankcase section on bench with
63
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ORDNANCE MAINTENANCE - ORDNANCE ENGINE
MODEL R975-C4 (CONTINENTAL)
Figure 62 — Removing Front Main Bearing Support
the No. 9 cylinder opening at the bottom. Rotate the crankshaft until
the counter-weights are opposite the No. 8 cylinder opening. Hold
master rod as near to center of No. 1 cylinder opening as possible.
Pull and lift assembly out of front of crankcase section twisting it
slightly to the right, to allow rear crank journal to slide out of the
journal bearing (fig. 72).
y. Remove Sump Drain Pipe and Fitting. Insert bar through
holes in sump fitting and unscrew fitting from crankcase (fig. 92).
Remove rubber seal from nipple connecting sump fitting to crankcase.
z. Remove Gam. Pull two cotter pins that lock cam hub bearing
support to rear main bearing (fig. 73). With wrench (41-W-871-31),
turn bearing support loose. Remove support and lift out cam (fig. 74).
Remove spacer from under cam.
aa. Remove Valve Tappets. Push each valve tappet in lower row
toward center of case. Use magnetized file, or screwdriver, and pull
64
TM 9-1725
9-10
DISASSEMBLY OF ENGINE INTO SUBASSEMBLIES
Figure 63 — Interior of Main Crankcase Section Prior to
Removal of Articulated Rods
roller pin and roller from tappets (fig. 75). Slide roller pin out from
inner end of tappet. Push each tappet through tappet guide and
remove from case. Push tappets in upper row toward center of case
and remove roller pins. Remove rollers and tappets from case.
ab. Remove Push Rod Housing Adapters. Unscrew and remove
the 18 push rod housing adapters (fig. 76). Remove seal from under
each adapter.
ac. Tappet Guides and Rear Main Bearing. These items are
shrunk into the crankcase, and should not be removed unless they
need to be replaced (par. 21 d (2) ).
10. REAR CRANKCASE AND DIFFUSER SECTIONS, RE-
MOVAL.
a. Remove Starter Gear and Shaft. Remove starter shaft nut
already loosened (par. 9 n). Working from the rear of the rear
crankcase section, pull starter shaft from bushing in rear section
(fig. 77). Working from front of diffuser section, pull starter gear
from bushing in diffuser section (fig. 78). CAUTION: When starter
shaft nut is removed, both starter gear and shaft are loose. Be sure
that neither assembly falls out of the crankcase section.
b. Remove Accessory Drive Gears. Remove cotter pins from
accessory drive gear nuts. Use a fiber block to keep gears from turn-
65
TM 9-1725
10
DISASSEMBLY OF ENGINE INTO SUBASSEMBLIES
f Tm
mj m
--a.
i ft
y- KNUCKLE PINS
j- PULLER, TOOL No. 41-P-2941-125
' V RATCHET
. ^.Gi**V*
LOCK FOR SCREWS
LOCK FOR KNUCKLE PINS
RA PD 314681
Figure 66 — Removing Knuckle Pin
ing. Break nuts loose with socket wrench (fig. 79). Remove nuts
and pull gears from shafts. CAUTION : Remove Woodruff keys from
gear shafts before proceeding further.
c. Removing Diffuser Section from Rear Crankcase Section.
Remove cotter pins from two nuts by accessory drive gear shaft which
hold diffuser section to rear crankcase section (fig. 80). Remove
nuts and fiat washers. Install three pullers (41-P-2906-280) through
tapped holes in diffuser section flanges (fig. 81). Turn pullers, and
separate diffuser and rear crankcase sections. Perform this operation
TM 9-1725
10
ORDNANCE MAINTENANCE - ORDNANCE ENGINE
MODEL R975-C4 (CONTINENTAL)
KNURLED NUT ' IGNITION HARNESS — 1 RA PD 314680
Figure 68 — Knurled Nut Holding Ignition Harness Together
68
MAIN CRANKCASE SECTION-' TREAR CRANKCASE SECTION RA PD 314684
Figure 69 — Removing Main Crankcase Section
carefully so as not to break off the diffuser section flanges. Remove
diffuser section from rear section (fig. 82 ).
d. Remove Rear Crankcase Section. Remove nuts from bolts
holding rear crankcase section to mounting stand, and place rear
section on inspection bench.
69
TM 9-1725
10
ORDNANCE MAINTENANCE - ORDNANCE ENGINE
MODEL R975-C4 (CONTINENTAL)
Figure 70 — Removing Main Crankcase Section with
Lifting Eye 41-E-615
70
CRANKCASE
SECTION
RA PD 3114671
Figure 71 — Main Crankcase Section before Removal of
Crankshaft Gear
TM 9-1725
10
ORDNANCE MAINTENANCE - ORDNANCE ENGINE
MODEL R975-C4 (CONTINENTAL)
TM 9-1725
10
DISASSEMBLY OF ENGINE INTO SUBASSEMBLIES
Figure 73 — Cotter Pins in Cam Hub Bearing Support
73
CAM HUB
NUT WRENCH
tSJ'
RA PD 314672
Figure 74 — Removing Cam Hub Bearing Support
Using Wrench 4I-W-871-31
74
VALVE TAPPET v — ROLLERS RA PD 314682
Figure 75 — Removing Valve Tappet Roller Pins
OIL SEAL— i /r- VALVE TAPPET GUIDES
TM 9-1725
10
ORDNANCE MAINTENANCE - ORDNANCE ENGINE
MODEL R975-C4 (CONTINENTAL)
Figure 77 — Removing Starter Shaft
76
Figure 78 — Removing Starter Gear
DIFFUSER
RA PO 314668
77
TM 9-1725
10
ORDNANCE MAINTENANCE - ORDNANCE ENGINE
MODEL R975-C4 (CONTINENTAL)
Figure 79 — Removing Accessory Drive Gears
78
TM 9-1725
10
DISASSEMBLY OF ENGINE INTO SUBASSEMBLIES
KEYS FOR ACCESSORY
Figure 80 — Diffuser Section Mounting Nuts
79
TM 9-1725
10
ORDNANCE MAINTENANCE - ORDNANCE ENGINE
MODEL R975-C4 (CONTINENTAL)
Figure 81 — Separating Diffuser Section from Rear Section
RA PO 314730
Figure 82 — Removing Diffuser Section
81
TM 9-1725
11-12
ORDNANCE MAINTENANCE - ORDNANCE ENGINE
MODEL R975-C4 (CONTINENTAL)
CHAPTER 4
DISASSEMBLY, CLEANING, INSPECTION, REPAIR,
AND ASSEMBLY OF SUBASSEMBLIES
Section I
INTRODUCTION
paragraph
Cleaning 11
Inspection . . 12
Repair 13
Assembly 14
11. CLEANING.
a. General. Use dry-cleaning solvent as a degreaser for cleaning
engine parts. After dry-cleaning solvent is used, coat parts with a
film of light oil to prevent corrosion or rusting. When steam-cleaning
the engine or engine assemblies, clean them immediately before dis-
assembly. For list of approved cleaners, refer to SNL K-l.
h. Antifriction Bearings. Abrasive dirt in bearing assemblies is
difficult to remove, so place bearings on perfectly clean bench either
before or after cleaning. Clean bearings in dry-cleaning solvent.
Slosh bearings around in the cleaner. Revolve bearings by hand
while bearing assembly is submerged to remove all grease, oil, or dirt.
Relubricate bearing after washing and draining. To relubricate, spin
bearings slowly by hand in clean new engine oil. Wrap cleaned,
oiled bearings in oiled paper, or place them in a dustproof container.
c. Oil-impregnated Bearings. Clean engine parts in which oil-
impregnated bearings are installed by immersing in dry-cleaning sol-
vent. Refill bearing pores with oil after each cleaning and before
re-use. To impregnate bearings quickly, heat a quantity of fresh
engine oil to 60° C. (140° F.), and submerge the part containing the
bearing in the oil for a period of 15 minutes.
12. INSPECTION.
a. Inspection Before Cleaning. Give parts an initial inspection
before cleaning, as dirt and deposits often indicate difficulties or im-
perfections which would not be visible if the part is clean.
b. Magnaflux Inspection. Have steel parts given a magnaflux
inspection. Do not have either ball or roller bearings magnafluxed.
The magnaflux machine operator must be a trained specialist.
c. Table of Limits. Use the Table of Limits exclusively to deter-
mine whether worn parts should be replaced. The table contains
wear limits beyond which parts should not be used.
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13
DISASSEMBLY, CLEANING, INSPECTION, REPAIR, AND
ASSEMBLY OF SUBASSEMBLIES
13. REPAIR.
a. Standard Practice. Certain repair instructions are standard
such as those applying to replacement of studs, polishing and recon-
ditioning of bearing or bushing surfaces, repainting housings, installa-
tion of liners, and bushings with the use of heat or dry ice, removal of
scratches, nicks, and burs, and replacement of synthetic rubber oil
seals and hose connections. The standard practices will not be
repeated under detailed repair instructions unless there is a deviation
from the standard.
b. Drive or Push Fit Parts. Where possible, assemble all parts
with a drive or push fit with the aid of heat or dry ice, or both. The
use of pullers is not recommended for the removal of drive or push
fit parts because of the nature of the materials involved. Use of
pullers may cause damage, and necessitate reaming new holes and
installing oversize parts. When using heat and ice for installations,
use oil or graphite grease to facilitate assembly. CAUTION : Do not
heat or cool parts excessively.
c. Emery Cloth. ■ Do not use emery cloth in reconditioning engine
parts, as abrasive particles are difficult to remove and injurious if
allowed to remain. Emery cloth may also cause scratches which may
develop into cracks.
d. Identification Numbers. Use care when marking position num-
bers on parts. Locate numbers in the area the manufacturer used
when the engine was assembled originally.
e. Machining Dimensions. , Where maximum and minimum limits
on any dimension are given in the text or in the Table of Limits,
attempt to obtain the mean dimension between the two limits.
f. Replacement of Studs. Use great care in the replacement of
steel studs in aluminum or magnesium alloy parts. Studs must be
removed without injury to the part in which the stud is set.
(1) Remove studs with stripped outside threads with stud driver
or small pipe wrench. Apply pressure on the handle of the tool used
so that there will be no tendency to bend the stud. Back the stud
out slowly to avoid overheating of the threads. Any thread lubricant
or sealing material used when the stud was installed is probably con-
gealed. Rapid withdrawal of the parts may damage the housing
threads.
(2) To remove studs broken off at or near the base, drill out center
section of the stud where size permits, and install square shanked stud
remover. Back stud out carefully, using a wrench of the proper size.
(3) Clean housing threads prior to installing new stud. Use tap
of correct size for this operation. Handle new taps carefully, as they
usually cut oversize. If the tap appears to be cutting material away
instead of just cleaning out the threads, withdraw it and use an older
83
TM 9-1725
13
ORDNANCE MAINTENANCE - ORDNANCE ENGINE
MODEL R975-C4 (CONTINENTAL)
tool. Rough edges or burs on a tap may also cause it to cut oversize.
Inspect all taps for evidence of rough edges or burs.
(4) If a stud was removed because it was loose, install next oversize
stud. Oversizes of 0.003 inch, 0.007 inch, and 0.012 inch are supplied.
Identify studs by machining on the end driven into housing. Examine
removed stud for size. Install next oversize stud available. If the
removed stud was broken and is not being replaced merely because
of loose fit, install replacement stud of same size.
(5) Apply a small amount of thread lubricant to. the threads on all
studs before installation.
(6) Before installing a stud, be sure it is the correct part, and
insert right end in housing.
(7) Be sure relief hole in bottom of stud bore is clear to prevent
hydraulic action when stud is driven. Hydraulic action may result
in cracking the case.
(8) When driving the stud, feed it in carefully until threads are
meshing properly. Turn stud in slowly and steadily until it is approxi-
mately in position. Use torque-indicating T-handle in conjunction
with the stud driver. Do not tighten stud to exceed torque limit
specified in the Table of Limits.
(9) Do not turn studs in rapidly. Threads may overheat and
seize or be damaged.
g. Removal of Scratches. Remove scratches on engine parts as
follows:
( 1 ) Handle parts carefully to prevent scratching.
(2) Remove small scratches in comparatively hard metals with
crocus cloth. Keep cloth wet with clean kerosene. Clean off a suffi-
cient amount of material to eliminate all traces of the original scratch.
Use a fine stone if necessary to completely remove deep scratches.
(3) Do not clean or polish the glazed surfaces of bushings unless
necessary to clean up scratches or scoring, or to provide specified
running clearances.
(4) Be sure to remove all nicks or burs when stoning gear teeth.
Stoning alters tooth profile and forms flat spots. Any alteration of the
contour on a gear tooth imposes heavy loads on the remaining high
spots and may lead to failure. Do not attempt to remove nicks, burs,
galling, or pitting below normal tooth surface. Replace severely
pitted or damaged gears.
li. Spare Pari Installation. Inspect spare parts to make sure that
oil passages are clear.
i. Machining Oilite Bushings. Never ream, scrape, bore, or
hand-burnish an oilite-type bushing. Reaming, scraping, or hand-
burnishing seals the pores and prevents proper seepage of lubrication
through bushing pores. Broach bushings to size.
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14
DISASSEMBLY, CLEANING, INSPECTION, REPAIR, AND
ASSEMBLY OF SUBASSEMBLIES
14. ASSEMBLY.
a. Cleaning Parts. Clean every part thoroughly with dry-clean-
ing solvent before installation. Oil part thoroughly. CAUTION:
Never use a cloth rag to wipe dust or dirt from parts. Lint from the
rag may clog oil lines or filters.
b. Pre-oiling. When an engine is started, it may require several
turns before the oil pump delivers a supply of lubricant to the farthest
points. For this reason, coat all parts with oil prior to assembly.
c. Torque Wrenches. Use a suitable torque-indicating wrench
when tightening any parts for which torque values are specified
(Table of Limits).
d. Standard Replacements. Always replace gaskets, hose, clamps,
lock wire, rubber oil seals, cotter pins, palnuts, and bolt head locking
straps.
e. Cotter Pin and Lock Wire Installation. Select cotter pins and
lock wire to fit snugly in drilled holes in which they are used. When
cotter pin is used to lock a castellated nut, set the locked end of the
pin inside the castellation; not outside or across it. Unless otherwise
specified, one tab of the cotter pin should be bent up and over flat
against the top of the bolt or stud. The other tab should be bent
down against the side of the nut. Twist lock wire evenly and draw it
up tightly. Loose lock wiring may vibrate enough during engine
operation to wear the wire through.
f. Castellated Nut Installation. Never back off a nut to line up
castellations with the safe-tying hole drilled in a bolt or stud. If the
nut must be tightened excessively, or the specified torque limit
exceeded, use a new washer or a new nut.
g. Free Movement of Parts. When building up a subassembly,
check for free movement after each moving part is installed and se-
cured. See that the part turns freely with no binding, rubbing, or
interference. If difficulty is noted, disassemble, locate, and correct
difficulty; then reassemble.
h. Assembly Order. Lock all bolts, nuts, and other parts requir-
ing it as the assembly progresses. Do not wait until subassembly is
completely built up. Some of the nuts may be missed. Complete
every assembly before leaving a job. As soon as each subassembly
is completed, plug all external openings and leave them plugged
until necessary to open them. This will prevent dropping nuts,
washers, and palnuts into the subassembly accidentally, and damag-
ing the engine when it is operated. Guard against small pieces of
lock wire getting into the engine when trimming ends with side cutters.
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ORDNANCE MAINTENANCE - ORDNANCE ENGINE
MODEL R975-C4 (CONTINENTAL)
Section II
FRONT CRANKCASE SECTION AND FRONT MAIN
BEARING SUPPORT
Paragraph
Disassembly 15
Cleaning 16
Inspection and repair 17
Assembly 18
15. DISASSEMBLY.
a. Remove Front Thrust Bearing. With a soft hammer, tap thrust
ball bearing from crankcase front section. No other disassembly is
required.
16. CLEANING.
a. Remove gasket compound from front main bearing support and
front crankcase section matching surfaces. Remove sludge from
breather hole in crankcase section. Clean all parts of the assembly
with dry-cleaning solvent, dry with compressed air, and coat with
light film of engine oil. When drying thrust bearing, be sure to blow
air stream through bearing at right angles to bearing races so as not
to spin the races.
17. INSPECTION AND REPAIR.
a. Front Crankcase Section. Using a magnifying glass, inspect
front crankcase section and lower half of engine support bar mounting
clamp for cracks (fig. 222). Inspect front and rear machined surfaces
for nicks or burs. Remove nicks and burs with a fine stone, and polish
with crocus cloth. Check for loose rivets on name plate and data
plate. Replace any loose rivets found. Inspect front crankcase studs
for tightness, condition of threads, evidence of stretching, and for
squareness. Remove and replace damaged studs (par. 13 f).
h. Front Section Cover. Inspect front section cover for condition
of casting and of machined surfaces. Replace cracked cover. Check
cover on surface plate for warpage, if galls are found on the front
cover bearing race that rides on roller bearing. Replace warped cover.
c. Thrust Bearing Nut. Inspect the thrust bearing nut for burs,
cracks, and thread condition. If nut is damaged at all, replace it.
Remove oil seal rings from thrust nut, and place them in the opening in
the front cover. Measure oil seal ring gaps. Gaps should measure
between 0.003 and 0.006 inch. Replace ring if gap for either ring
exceeds 0.006 inch.
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DISASSEMBLY, CLEANING, INSPECTION, REPAIR, AND
ASSEMBLY OF SUBASSEMBLIES
d. Front Cover Shim. Inspect front cover laminated shim
(fig. 222) for breaks. Replace shim if any breaks are found.
e. Thrust Bearing. After cleaning bearing (par. 16 a), inspect
the condition of balls and races with a magnifying, glass. Turn bear-
ing assembly slowly to check for pits, smoothness, flat spots, or exces-
sive wear. Replace bearing if cracks, chips, or pits are found. If
bearing assembly is satisfactory, oil thoroughly and wrap it in oiled
paper to protect it from dust until assembled into engine.
f. Main Bearing Support.
(1) Front Main Bearing Support (fig. 222). Inspect front
main bearing support for cracks, and replace if damaged. Check fit
of front main bearing support to the front and main crankcase sections
by placing one section on top of the other. Check the front main
bearing support parting flanges for nicks, burs, and roughness. Re-
move burs and rbugh spots with fine stone. Examine oil deflector
plate for cracks around the flange, and check the condition of the
lock wire on the four retaining screws. If the deflector is cracked,
replace it. If the lock wire is broken, replace it, and check the tight-
ness of the retaining screws.
(2) Front Main Bearing. Inspect the surfaces of the outer race
of the front main bearing for scoring and galling. Remove slight
scores and galls with fine stone. Do not attempt to remove heavy
scores or galls, but replace race and roller assembly. Check rollers
for pits and flat spots, by testing operation of rollers on inner race
still installed on the crankshaft. If rollers are pitted, or have flat
spots, replace bearing assembly. For removal of front main bearing
inner race, refer to paragraph 3 1 i.
(3) Front Main Bearing Support Ring (fig. 222). Remove
any rough spots from front main bearing support ring with crocus
cloth. Insert bearing in ring and check clearance. If clearance ex-
ceeds 0.0015 inch, replace support ring. Drill out ring pins and drive
ring from support. Drive ring out evenly from both sides. Heat
bearing support to 250° F., and freeze new support ring in dry ice,
or ice water, if dry ice is not available. Center ring in support making
certain that it is flush with the edges of the support at both sides.
Allow support to cool. Drill three holes from 0.186 to 0.187 inch in
diameter through the ring and into bearing support. Drill holes to a
depth of from 0.560 to 0.590 inch. Space holes midway between old
pin holes, and drill them at an angle of approximately 20 degrees to
the face of the support. Pins should be several thousandths of an inch
larger than the holes to provide a drive fit. Drive pins into holes
until heads of pins are slightly below face of ring. Remove any nicks
and burs around pin holes, and polish with crocus cloth. Place ring
support in lathe, and center it from the outside flange, so that as the
87
TM 9-1725
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ORDNANCE MAINTENANCE - ORDNANCE ENGINE
MODEL R975-C4 (CONTINENTAL)
support ring is bored, it will be concentric with flange. Bore ring
diameter to between 5.5116 and 5.5126 inches for proper bearing fit.
If bearing clearance is within limits, check support ring to see that it
is tight in support. If ring is loose, install new pins. Drill new pin
holes midway between present pins and proceed as explained above.
18. ASSEMBLY.
a. The front crankcase and front main bearing support are not
assembled at this timel For assembly procedure, refer to chapter 5.
Section III
MAIN CRANKCASE SECTION
Paragraph
Disassembly 19
Cleaning 20
Inspection and repair 21
Assembly 22
19. DISASSEMBLY.
a. The main crankcase assembly has already been completely
disassembled except for the rear main bearing, and valve tappet
Figure 83 — Main Crankcase Section
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DISASSEMBLY, CLEANING, INSPECTION, REPAIR, AND
ASSEMBLY OF SUBASSEMBLIES
Figure 84 — Checking Hear Main Bearing Diameter
guides, which should not be removed unless it is necessary to replace
them. If one or more valve tappet guides and the rear main bearing
need replacing, replace them at the same time. This will necessitate
heating the case only once.
20. CLEANING.
a. Steam-clean the main crankcase section. Clean the case and
valve operating mechanism parts with dry-cleaning solvent. Coat
parts with thin film of engine oil.
21. INSPECTION AND REPAIR.
a. Main Section Casting. Inspect main section casting for cracks.
Pay particular attention to intercylinder webs, cylinder pads, tappet
guide webs, and flanges (fig. 83). Replace main section if it is cracked
or for any reason unserviceable. Inspect all flanges and machined
surfaces for nicks, burs, or roughness. Remove nicks or burs with a
fine stone, and polish with crocus cloth. Using a dial indicator
mounted on pilot at main bearing, check case for concentricity at the
front and rear flanges. Replace case if it is out of round more than
0.003 inch. Check studs for tightness and thread condition. Replace
loose, or worn, studs (par. 13 f). Inspect pressed-in oil line for tight-
ness and condition. Blow out line with compressed air. Blow out
89
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ORDNANCE MAINTENANCE - ORDNANCE ENGINE
MODEL R975-C4 (CONTINENTAL)
tappet guide oil drain holes to make certain they are clear.
b. Rear Main Bearing. Inspect rear main bearing for looseness.
Check surface of bearing for scoring or indications of wear. Inspect
the condition of the threads of the cam hub bearing support. Meas-
ure the diameter of the rear main bearing with micrometer or plug
page (fig. 84). If diameter does not measure between 3.2215 and
3.2225 inches or if bearing is scored or otherwise damaged, replace
bearing. If bearing does not have to be replaced, check the dowel
which locks the bearing to the crankcase (fig. 85). If dowel is loose,
knock it out with punch, and press in an oversize dowel. After the
oversize dowel has been installed, peen the main bearing flange
slightly over the head of the dowel.
c. Replace Rear Main Bearing.
(1) Remove Bearing. Place crankcase section in oven and heat
to 300° F. Remove crankcase section from oven. Slide out bearing
and dowel. Select and check fit of new bearing. Refer to the Table
of Limits for proper bearing and bore dimensions. If the inside
diameter of the bearing bore is oversize, use an oversize bearing, and
ream the bearing bore to the proper size to receive oversize bearing.
(2) Install Bearing. Shrink new bearing with dry ice or ice
water. Place crankcase in oven and heat to 300° F. Remove crank-
99
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DISASSEMBLY, CLEANING, INSPECTION, REPAIR, AND
ASSEMBLY OF SUBASSEMBLIES
Figure 86 — Seating Rear Main Bearing with Puller
(Replacer) 41-R-2373-675
case from oven. Install pilot in bearing locking dowel hole. Slide
bearing into position so that cutaway for bearing dowel fits over
pilot. Using bearing puller, carefully press bearing into position so
that the bearing flange is shouldered on the front face of the crank-
case section (fig. 86). Be sure the threads on the outside diameter
of bearing are not damaged. Remove pilot. Drive a new dowel pin
into position. Use an oversize dowel pin, if necessary, to secure a
tight press fit. Allow crankcase section to cool. Peen the bearing
flange slightly over head of dowel to secure dowel in place. Plug oil-
holes in bearing with paraffin. Install front crankcase section. Install
reamer fixture supports (41-F-2994-21) in main crankcase and front
crankcase sections and install reamer (fig. 87). Ream bearing to
between 3.2215 and 3.225 inches (fig. 88). Remove reamer and
supports. Remove front crankcase section. Smooth up inside diam-
eter of bearing with crocus cloth. Clean paraffin from oilholes and
clean out passages with compressed air.
d. Valve Tappet Cuides.
(1) Inspect Valve Tappet Guides. Using inside micrometer, or
special plug gage, measure inside diameter of valve tappet guides
(fig. 89). Replace any guide if it is worn beyond allowable limits
(0.6876 to 0.6883 inch). Check guides for cracks, alinement, and
tightness in crankcase section. Replace guide if it is loose or cracked.
91
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ORDNANCE MAINTENANCE - ORDNANCE ENGINE
MODEL R975-C4 (CONTINENTAL)
2
n
92
Figure 87 — Fixtures and Reamer Installed for Reaming Rear Main Bearing
TM 9-1725
21
ORDNANCE MAINTENANCE - ORDNANCE ENGINE
MODEL R975-C4 (CONTINENTAL)
TM 9-1725
21
DISASSEMBLY, CLEANING, INSPECTION, REPAIR, AND
ASSEMBLY OF SUBASSEMBLIES
Examine inner surfaces of guides for scores. Smooth out slight
scores with special hone (fig. 90) or crocus cloth wrapped around
tool. Check all guides for cleanliness of oilholes.
(2) Replace Valve Tappet Guides. Drill out valve tappet
guide until a shell approximately 0.015 inch thick remains. Break
out remaining shell, being extremely careful not to mar the guide
bore in the crankcase. Pick replacement guide. Shrink guide in
dry ice or ice water. Place crankcase section in oven and heat to
300° F. Replace guides with rear main bearing if bearing needs to be
replaced (par. 19 a). Remove crankcase from oven, and insert guide
in guide opening. Aline slots at the inner end of the guide with alining
bar (41-B-332) (fig. 91). Be sure that the guide flange is bottomed
in its recess.
e. Valve Tappets (fig. 235). Inspect sliding surfaces of valve
tappets for wear or scoring. Check tappets for cracks, especially
around roller pin holes. Inspect rollers and roller pins very carefully
for cracks, pits, or flat spots. Check condition of push rod sockets.
Pay particular attention to the push rod seat in the socket. See that
oilhole through the socket is clear and not obstructed. Inspect push
rod socket springs. See that the springs are not broken, that they are
of the proper length, and have proper tension. At a length of 2.18
inches, spring tension should be between 7.74 and 9.46 pounds. If
tension is less than 6 pounds, replace spring. Replace any unservice-
able parts.
f. Cam Huh and Ring Assembly.
(1) Inspect Cam Hub, Ring, and Gear (fig. 235). Inspect cam
hub and ring assembly for cracks. Replace assembly if cracks are
found. Check rivets to see that they are tight. If loose rivets are
found, install new ones. Inspect cam lobes for wear and evidences of
pounding. If lobes are worn or damaged, replace assembly. Ex-
amine gear by magnaflux for cracks, and visually for worn or broken
teeth. Replace worn or damaged gears. Examine outer surface of
hub bearing support for wear, burs, and condition of threads on the
inside diameter of support. Clean up light burs and rough spots with
fine stone, and polish with crocus cloth. Check cam hub bearing
spacer for burs, roughness, and uniform thickness. Replace any un-
serviceable part. Check smoothness of cam bearing inner surfaces.
Measure inside diameter of bearing with micrometer, or plug gage.
Clearance between cam hub and cam hub bearing should measure
between 0.0015 and 0.0045 inch, tight fit. If clearance is not between
these limits, replace bearing. If inside diameter of bearing is greater
than permissible limits (Table of Limits) or surface is scored, replace
bearing.
(2) Remove Cam Bearing. Insert cam ring in lathe with cam
95
RA PD 314755
TM 9-1725
21
ORDNANCE MAINTENANCE - ORDNANCE ENGINE
MODEL R975-C4 (CONTINENTAL)
RUBBER SEAL
MAIN SUMP FITTING
\ ADAPTER —i I
TWStmmjsL
Cl
|M
||§p . — Tl‘
^ \M
■> j
* JrnBjk
^ a
9 9
sBjfiBBsH /kr~"
■1 fl
1JI
RA PD 314801
Figure 92 — Oil Sump Fitting Removed
PRESSED-IN OIL LINE
OIL DRAIN HOLES
TAPPET GUIDES
Figure 93 — Cleaning Valve Tappet Guide
side against fixture. Center assembly in lathe. Make all centering
adjustments from the pitch line of the gear teeth. To do this, place
a 0.184-inch diameter pin between any two teeth of the external gear.
After centering assembly, bore out bearing so as to leave a shell
^approximately 0.015 inch thick. Break out thin shell, being careful
not to damage cam hub bore. After removing bearing, drive out hub
bearing pins. Polish the inside diameter of the hub especially around
the pin holes.
96
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DISASSEMBLY, CLEANING, INSPECTION, REPAIR, AND
ASSEMBLY OF SUBASSEMBLIES
Figure 94 — Testing Valve Tappet Fit
(3) Install Cam Bearing. Heat the cam hub in hot oil for 15
minutes. Relieve the entering edge of the steel-back bearing with a
file, and smooth with fine emery cloth. Place a light coating of oil
on the steel back. Remove hub from hot oil, and with the oilholes in
the bearing lined up with the oilholes in the hub, within Vt 0 of an
inch, press in bearing to within Y 32 inch from the counterbore in the
long end of the hub. Pack all oilholes with paraffin to prevent chips
from entering oil passages. Drill a 0.183-inch hole through bearing at
each of three pin hole locations in hub. Drill hole at an angle of 20
degrees. Drive 0.186-inch pin in each pin hole, and peen metal
around pin holes lightly to secure pins. Set up cam assembly in lathe
as previously explained. Bore out bearing to an inside diameter of
from 3.8745 to 3.8755 inches.
22. ASSEMBLY.
a. Install Sump Fitting. Place new rubber seal on fitting nipple
and fitting in crankcase (fig. 92). Place bar through holes in fitting
and screw fitting into crankcase.
b. Install Push Rod Housing Adapters (fig. 76). Place new rub-
ber seal on push rod housing adapters. Position end of adapters over
crankcase opening and screw adapters into crankcase. After screw-
ing each adapter into case, run finger through adapter to make sure rub-
ber seal is properly positioned.
c. Install Valve Tappets. Wrap clean cloth around a rod of suit-
able size, insert in tappet guide openings, and clean them out thor-
oughly (fig. 93). Make certain that each valve tappet is clean, and
insert it in its matching guide (fig. 94). Tappets should fit so that
97
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ORDNANCE MAINTENANCE - ORDNANCE ENGINE
MODEL R975-C4 (CONTINENTAL)
Figure 96 — Installing Cam Hub Bearing Support
when they are tapped lightly with finger, they will slide back or forth
from one end of the guide to the other. If any tappet will not slide
back and forth in guide, polish inside of tappet guide with crocus
cloth to remove any roughness. After checking the fit of tappets, re-
98
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22
DISASSEMBLY, CLEANING, INSPECTION, REPAIR, AND
ASSEMBLY OF SUBASSEMBLIES
CAM HUB BEARING SUPPORT—' FEELER GAGE — * RA PD 314759
Figure 97 — Measuring End Play of Cam Using Gage 4I-G-400
move them one at a time, and oil tappets and tappet guides. Rein-
stall each tappet in the guide in which it was fitted, and move them
towards the center of the crankcase until the roller pin holes are clear
of the guides. Insert rollers and push pins through rollers and tappets
(fig. 75). Slide tappets outward until roller pins are supported in
guides.
d. Install Cam Assembly.
(1) Install and Check Clearance. Place spacer for cam hub
bearing over main bearing extension (fig. 95). Place cam ring on
spacer. Install cam bearing support on rear main bearing extension
(fig. 96), and tighten support with wrench. Check the clearance
between the cam bearing support and the upper face of the cam bear-
ing with a feeler gage (fig. 97). Clearance should measure between
0.003 and 0.005 inch, loose fit. If clearance exceeds 0.008 inch, re-
place bearing.
(2) Adjust Tappet Rollers. Check position of cam lobes
against tappet rollers. If rollers do not ride squarely on lobes, change
the cam hub bearing spacer (fig. 95). If spacer is too thick, grind
it to proper thickness. If spacer is too thin, replace with one of proper
thickness. Spacer is of proper thickness when tappet rollers ride
squarely on cam lobes.
(3) Complete Installation. Using a % 4 -inch drill, bore two
holes in rear main bearing extension to line up with holes in cam hub
99
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ORDNANCE MAINTENANCE - ORDNANCE ENGINE
MODEL R975-C4 (CONTINENTAL)
Figure 98 — Drilling Main Bearing Extension for Cotter Pins
bearing support (fig. 98). The holes should be directly opposite each
other and not closer to another hole than s /g inch. Remove cam
bearing support and cam ring, and break any sharp edges from holes
drilled in rear main bearing extension. Clean all drillings from crank-
case, bearing support, and cam ring. Lubricate all parts with light
engine oil and reinstall. Insert two cotter pins through cam hub
bearing support and through bearing extension. Cut off and remove
ends of cotter pins. Cotter pins must not extend through bearing
support more than Va inch. Spread cotter pins, and bend prongs to
follow radius of rear main bearing extension so that they will clear
crankshaft when it is installed. Cover main crankcase assembly to
protect it from dust until ready to install on diffuser and rear crank-
case sections.
Section IV
CYLINDERS, VALVES, AND VALVE OPERATING
MECHANISMS
Paragraph
Disassembly 23
Cleaning 24
Inspection and repair 25
Assembly 26
23. DISASSEMBLY.
a. Remove Oil Seals. If oil seal ring on lower side of cylinder
mounting flange has not been removed, remove and discard it at this
time. Remove oil seal ring from each cylinder as it is disassembled.
100
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DISASSEMBLY, CLEANING, INSPECTION, REPAIR, AND
ASSEMBLY OF SUBASSEMBLIES
EXHAUST ELBOW — J
CYLINDER ASSEMBLY— 1
Figure 99 — Removing Exhaust Elbow
I». Remove Exhaust Elbows. Cut and remove safety wire from
four nuts securing exhaust elbow to cylinder studs. Remove nuts and
flat washers, and lift off exhaust elbow. Remove all exhaust elbows
in same' way (fig. 99).
c. Remove Valve Springs.
(1) Using Fixture. Place cylinder assembly over valve assembly
stand (41-S-4988-77) (fig. 100). Lower fixture bar until valve
springs are compressed. Remove split valve lock. Raise fixture bar
and release compression on valve springs. Lift off valve spring outer
washer and the three valve springs. Ordinarily, the inner valve spring
washer remains in cylinder. Remove washer and springs for valve
in all other cylinders in same way.
(2) Using Compressor. Place cylinder assembly over wood
block. Install valve spring compressor (41-C-2559-25) on one of
the rocker boxes by inserting compressor pin through rocker arm hub
bolt holes (fig. 101). Pull down on compressor lever until cam action
of lever holds valve springs compressed. Remove split valve lock (fig.
101). Raise up compressor lever and release valve springs. Take
compressor off rocker box. Remove valve spring outer washer and
the three valve springs. Remove other valve springs in same way.
cl. Remove Valves. Remove and discard circlet from upper end
of each valve stem (fig. 102). Hold both cylinder valves so they
cannot slide out through valve guides, and lift cylinder from assembly
block. Lay cylinder on its side. Before withdrawing valves from
valve guides, inspect each valve stem to make certain it is free from
101
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23
ORDNANCE MAINTENANCE - ORDNANCE ENGINE
MODEL R975-C4 (CONTINENTAL)
VALVE SPRING
COMPRESSOR
CYLINDER
ASSEMBLY
VALVE ASSEMBLY FIXTURE
Figure 100 — Compressing Valve Spring in Valve
Assembly Fixture
103
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ORDNANCE MAINTENANCE - ORDNANCE ENGINE
MODEL R975-C4 (CONTINENTAL)
Figure 103 — Loosening Packing Nut on Drain Tube
burs, or other damage. If any valve stem is damaged, clean it up with
fine stone before withdrawing the stem from valve guide. Withdraw
valves from guides one at a time. Remove valves from all cylinders
in same way. Tag each valve with the number of the cylinder from
which it is removed.
e. Remove Oil Drain Tubes. Remove any oil drain tube between
cylinder rocker boxes which shows evidence of damage or leakage
at the seals. Loosen packing nuts at both ends of drain tube (fig. 103)
with spanner wrench. Slide packing nuts, seals, and washers up on
tube. Slide tube into one rocker box to disengage other end of tube
(fig. 104). Rotate tube and pull end out of other rocker box. Clean
out rubber seal or fragments of seal from recess in rocker box.
(1) Cylinder and Head Assembly. Do not attempt to remove
cylinder head from cylinder barrel.
24. CLEANING.
a. Steam-clean each cylinder assembly to remove grease and dirt.
Clean all disassembled' parts in dry-cleaning solvent. Be sure to coat
parts with light engine oil after drying to prevent parts from rusting.
Remove carbon from interior of cylinders. Clean rocker arm bearings
with dry-cleaning solvent, and dry with air hose. Coat bearings with
light cylinder oil. Be sure to clean dirt from between fins of cylinder
104
TM 9-1725
24-25
DISASSEMBLY, CLEANING, INSPECTION, REPAIR, AND
ASSEMBLY OF SUBASSEMBLIES
Figure 104 — Removing Rocker Box Drain Tube
heads and muffs, and exhaust elbow fins. Polish carbon from heads
of all valves and valve stems, using a wire brush.
25. INSPECTION AND REPAIR.
a. Rocker Box Assemblies.
(1) Rocker Box Covers. Inspect rocker box covers (fig. 105)
for warped parting surface, burs, and cracks. Replace cracked rocker
box covers. If parting surface of any cover is burred, clean up rough
spots with fine stone, and polish with crocus cloth.
(2) Oil Drain Tubes. Inspect oil drain tubes for cracks, bends,
dents, and leaks. Replace damaged tubes.
(3) Push Rod Housing Connectors. Inspect push rod housing
connectors. If any connector is bent or damaged, replace the cylinder.
(4) Rocker Arms and Rocker Arm Bearings (fig. 236). Ex-
amine rocker arms for cracks, scratches, nicks, and chafing. Check
rocker arm rollers for cracks, flat spots, and fit on roller pin. If roller
appears to be loose on pin, check with dial indicator. If looseness ex-
ceeds 0.0025 inch, loose fit, replace roller. Check to see that roller
pin is tight in arm. Inspect rocker arm threads at the adjusting
screw for burring and general condition. Inspect adjusting screws
and lock nuts for cracks and thread condition. Inspect push rod ball
socket in adjusting screws for wear. Replace arm assembly if rocker
arm is cracked, or if rocker arm rollers are cracked, have flat spots,
or are loose. If threads of adjusting screws are burred, dress threads
105
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25
ORDNANCE MAINTENANCE - ORDNANCE ENGINE
MODEL R975-C4 (CONTINENTAL)
V — - CYLINDER BASE PACKING RING RA PD 314850
Figure 105 — Cylinder — Disassembled
TM 9-1725
25
DISASSEMBLY, CLEANING, INSPECTION, REPAIR, AND
ASSEMBLY OF SUBASSEMBLIES
with fine stone. If push rod ball socket in any adjusting screw is
worn, replace adjusting screw! If push rod ball socket is burred, polish
it with crocus cloth. Make sure oilhole leading from adjusting screw
opening through length of rocker arm is clear. Check tightness of
rocker arm bearings. Replace bearing if it is so loose it can be pushed
out by hand, if it is rough, or if it has flat spots. Check for flat spots
or roughness by rotating bearing slowly. To replace bearing, heat
rocker arm in oil bath at 250° F., and remove bearing. Place rocker
arm in arbor press, with chamfered end of bearing bore facing up.
Press new bearing into bore.
(5) Rocker Arm Hub Bolts. Give rocker arm hub bolts magna-
flux inspection for cracks. Replace cracked bolts. Inspect hub bolts
for scores and thread condition. Check fit of bolts in rocker box and
hub bearing support holes. Clean up nicks and burs on bolts and
threads with fine stone. Install new spacing washers when assembling
hub bolts and rocker boxes.
h. Push Rod Assemblies (fig. 235).
(1) Push Rods. Inspect push rods for cracks and cleanliness of
oilholes. Inspect ball ends for cracks, looseness in the rod, and wear.
Replace cracked rods. Check rods for bends by rolling rods on sur-
face plate. Tap slightly bent push rods with a light rawhide mallet,
until they are straight, checking straightness on surface plate. Polish
ball ends with crocus cloth. If ball end fits loosely in rod, replace rod
assembly. Clean out oilholes. Inspect push rod springs. Replace
broken springs, or springs which do not have the compression pre-
scribed. At a length of 2.18 inches, spring pressure should be between
7.74 and 9.46 pounds.
(2) Push Rod Housings. Inspect push rod housings for dents
and cracks. Replace cracked housings. Straighten slight dents in
push rod housings by placing a metal rod of the proper size and shape
inside housing, and hammering out dents. Do not reduce wall thick-
ness appreciably. Replace all push rod housing hose, hose connec-
tions, and hose clamps.
c. Cylinders.
( 1 ) Mounting Surfaces. Inspect the parting surface on each
rocker box, exhaust elbow mounting pad, and fuel induction tube
flange mounting for scratches, nicks, and for high spots around the
rocker box and exhaust elbow studs (fig. 105). Remove nicks, burs,
or high spots with fine stone, and polish with crocus cloth.
(2) Mounting Studs. Inspect rocker box and exhaust elbow
mounting studs for straightness, tightness, evidence of stretching, and
condition of threads. Replace any loose or damaged mounting stud.
Follow standard procedure for replacing studs (par. 13 f).
(3) Rocker Arm Hub Bolt Bosses. Inspect rocker arm hub
107
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ORDNANCE MAINTENANCE - ORDNANCE ENGINE
MODEL R975-C4 (CONTINENTAL)
bolt bosses for cracks, nicks, or burs (fig. 104). Clean up nicks or
burs, with a fine stone, and polish with crocus cloth. Check inside
diameter of rocker hub bolt holes for wear.
(4) Cylinder Heads (fig. 105). Inspect all cylinder heads in-
ternally and externally for cracks. Look for cracked or broken fins.
If cylinder head is cracked, replace cylinder. Rework cracked or
broken fins by profiling the metal to depth of crack, provided crack
does not extend into cylinder head dome, and only a small amount of
metal needs to be removed. Replace any cylinder in which a fin
crack extends into the head dome, or in which an appreciable area
of fin metal must be removed to make the repair.
(5) Valve Guides. Inspect valve guides for tightness in cylinder
head, backing out, cracks, and scoring of the inside diameter. With
micrometer or special plug gage, measure inside diameter of valve
guides for wear, out of round, or belling out at the ends (fig. 106).
Measure guide diameter at two locations, 90 degrees from each other,
at each end of guide, to determine out of round condition. Replace
guides which are damaged, worn beyond allowable limits, or are out
of round. Intake guides should have an inside diameter measuring
between 0.530 and 0.531 inch; exhaust guides an inside diameter
measuring between' 0.6235 and 0.6245 inch. To replace guide, drill
guide until a shell approximately 0.015 inch thick remains. Break
out shell, being careful not to damage guide retaining hole. Various
sized replacement guides are provided. Select replacement guide,
and ream retaining hole so that the guide will fit the hole tightly.
Heat the cylinder to 300° F. Freeze the guide. Install guide in re-
taining hole ’making sure that it is properly seated. Allow cylinder
to cool. Ream inside diameter of guide to fit valve stem. Clean
guide bore with crocus cloth, and reseat valve seats (subpar. (6 )£>,
below). NOTE: Replacement of valve guides is normally a manufac-
turer’s operation performed at time of cylinder barrel replacement.
(6) Exhaust and Intake Valve Seat Inserts.
(a) Inspect Valve Seat Inserts. Inspect valve seat inserts in
all cylinders for pitting, burning, and to see that they are concentric
with their valve guide. Reseat or replace any severely pitted or
burned insert.
(b) Reseat Valve Seat Inserts. Place cylinder in suitable re-
seating fixture. Locate grinding wheel pilot in valve guide to insure
proper relation between insert and valve guide angles. Dress insert
with grinding wheel very accurately to an angle of 45 degrees. After
reseating insert, check concentricity of seat with a blue gage and
Prussian Blue. The gage must be constructed so that it checks the
angles of the valve seat insert and the valve guides.
(c) Replace Valve Seat Inserts. Replace any insert which
cannot be reseated to fit. Replace insert by mounting cylinder in drill
108
TM 9-1725
25
DISASSEMBLY, CLEANING, INSPECTION, REPAIR, AND
ASSEMBLY OF SUBASSEMBLIES
Figure 106 — Measuring Valve Guide Using Gage 4I-G-254-285
press fixture. Attach it with the hold-down clamps. Position cylinder
by means of cradle lock nuts, adapter clamps, and indexing pins, so
that valve seat boring tool is vertical when inserted in the guide.
Adjust the seat cutter so that it will remove all but a thin shell on the
outer diameter of the seat. Break out the' remaining shell, and clean
up the seat recess. Measure the diameter of the seat recess and the
outside diameter of the replacement valve seat. Refer to Table of
Limits for desired shrink fit. Bore out seat recess to accommodate
nearest oversize seat. Seats are furnished in four oversizes ranging
from 0.010 to 0.040 inch. Place cylinder in oven, and heat it to not
more than 400° F., for 1 hour. Install new valve seat on inserting
tool with puller and handle, and chill seat to 20° F., for approximately
20 minutes. Remove cylinder from oven, and insert new seat. Pull
seat into place with inserting tool. Do not remove tool until cylinder
head has cooled sufficiently to grip seat. Remove inserting tool and
allow cylinder to cool in air. Face new valve seats after installation
as explained in subparagraph (b) below.
(7) Valves.
(a) Inspect Valves. Have intake valves magnafluxed for cracks.
Inspect exhaust valves for cracks, visually. Inspect valve heads and
faces for pitting, scoring, burning, wear, and warpage, and valve faces
for thin edges. Check valve stems for nicks, burs, and warpage.
Measure diameter of each stem with micrometer to make sure that
the diameter is uniform over the entire length of the stem, and that
109
TM 9-1725
25
ORDNANCE MAINTENANCE - ORDNANCE ENGINE
MODEL R975-C4 (CONTINENTAL)
1. CYLINDER BORE GAGE INSTALLED ON CYLINDER
RA PD 314722
Figure 1 07 — Checking Cylinder Bore Diameter
it is the proper size to fit the valve guide. Intake valve stem diame-
ters should measure between 0.5282 and 0.5287 inch; exhaust valve
stems between 0.6195 and 0.6200 inch. Remove all nicks and burs
from valve with a fine' stone. If valve head or face is badly warped,
burned, or worn too thin to reface, replace them. Bury old sodium-
filled valves in the ground to avoid possible fires or injury to person-
nel. Never include sodium-filled valves with other parts turned in
for salvage or disposal as scrap. If valve is slightly pitted, scored, or
burned, reface the valve.
(b) Reface Valves. Place valve in refacing machine, set to grind
valve face to an angle of from 44 degrees to 44 degrees 15 minutes.
Grind face of valve, being sure not to remove any more metal than
necessary. Reface valve very accurately. Check valve for face angle
with dial indicator, or other suitable gage. When refacing the valve,
if the edges of the face are ground too thin, replace the valve. CAU-
TION: Exhaust valve stems are filled with sodium which is inflam-
mable in presence of water. Use extreme care when disposing of
discarded exhaust valve.
110
TM 9-1725
25
DISASSEMBLY, CLEANING, INSPECTION, REPAIR, AND
ASSEMBLY OF SUBASSEMBLIES
(8) Valve Springs, Washers, and Locks (fig. 108). Inspect
valve springs for cracks, scores, pitting, and breakage. Test the ten-
sion of each spring in a valve spring tension testing machine. Discard
any outer spring with a tension less than 90 pounds, at a spring height
of 1.34 inches; any intermediate spring with a tension less than 69
pounds, at a height of 1.40 inches; and any inner spring with a tension
less than 35 pounds, at a height of 1.32 inches (Table of Limits).
Give valve spring washers a magnaflux inspection for cracks. Inspect
washers visually for burs and excessive wear. Inspect valve spring
locks for cracks, burs, and wear. Replace unserviceable springs,
washers, or locks.
(9) Cylinder Barrels. Inspect exterior of cylinder barrels for
bent, scratched, or broken skirts or fins. Inspect cylinder mounting
flange for cracks, nicks, and warpage. Replace any cylinder with a
bent or cracked skirt, or with barrel fins broken at the root of the fin.
Replace any cylinder with a cracked or warped flange.
(10) Cylinder Bores. Inspect the inside diameter of the cylin-
der barrel in all cylinders for corrosion, scores, ring wear, and out-of-
round condition. Measure cylinder bore diameter with cylinder bore
gage (41-G-99-500) and ring (41-R-2492) (fig. 107). Cylinder bar-
rels are of the choke type and are approximately 0.009 inch smaller
at the top than at the bottom, to compensate for the increased expan-
sion of the upper part of the bore at operating temperatures. For this
reason, measure the bore at room temperature (70° F.) parallel to
the piston pin, and 90 degrees to the piston pin 8 V 2 , 8 Vi, 8 , 7%,
7 1 /*, 6y 4 , 53/4, 5V4, 43/4, 41 / 4 , 33/4, 31 / 4 , 23/4, 21 / 4 , PA, DA, and
3/i inches from the bottom of the cylinder. The difference between
the reading for the 8 V 2 inch measurement and the 3 / 4 inch measure-
ment gives the choke. Measure the choke for each cylinder. If cylin-
der choke is less than 0.004 inch, but is worn irregularly, hone bore
until irregularities have been cleaned up. If choke is worn beyond
the allowable limits and cannot be cleaned up to within the allowable
limits, replace cylinder.
(11) Exhaust Elbows. Examine exhaust elbows for cracks, ero-
sion, and condition of fins (fig. 99). Replace damaged elbows. In-
spect parting surfaces for nicks, burs, and warpage. Remove nicks
and burs from parting surfaces with fine stone and polish with crocus
cloth. Replace elbow if parting surface is warped.
(12) Spark Plug Inserts. Check spark plug inserts for tight-
ness and condition of threads. If any spark plug insert is cracked,
damaged, or loose, do not attempt to replace it, but replace cylinder.
Replacing spark plug inserts is a difficult, complicated procedure and
should not be attempted.
(13) Sump and Sump Drain Tubes (fig. 242). Inspect oil sump
assembly, particularly at mounting flange locations. Check sump
111
TM 9-1725
25
ORDNANCE MAINTENANCE - ORDNANCE ENGINE
MODEL R975-C4 (CONTINENTAL)
-VALVE —.VALVE SPRING
LOWER WASHER
INTERMEDIATE
VALVE SPRING
OUTER VALVE SPRING
INNER VALVE SPRING
VALVE SPRING
UPPER WASHER-
Figure 108 — Valve Assembly — Disassembled
tanks with pressure, if possible, for leaks, dents, and other damage.
Inspect connecting tubes for leaks, dents, and damage. Replace dam-
aged tanks or tubes. Replace all attaching hose and hose clamps.
(14) Fuel Induction Tubes. Inspect induction tubes for cracks,
bends, dents, and leakage holes along the welded seam (fig. 14).
Plug one end of tubes and apply air pressure to the other end. Check
the welded seam. Straighten tubes that are not badly bent, or dented.
Replace tubes that are cracked, badly dented, or which leak. Inspect
flame arrestor for condition. Blow compressed air through the length
of the tube to clean out any foreign matter lodged in the flame ar-
restor. Examine mounting flanges for cracks, warpage, and condition
of finished surfaces. Replace tubes which have badly warped, cracked,
or scratched flanges. Check condition of cap screw mounting
holes. Remove slight nicks and burs from machined surfaces with a
fine stone. Remove and discard old rubber seal from end of induc-
tion tube. Remove gland nut and inspect it for condition of threads,
and for bent or mutilated conditions. If nut is damaged, install new
nut. Install new rubber seal on end of tube at this time.
(15) Primer System (fig. 244). Disconnect primer connecting
lines from distributor. Blow compressed air through lines to make
sure they are clear, and that there are no sharp bends to obstruct
openings. Check each line for leaks and loose fittings. Blow com-
pressed air through distributor to make sure openings are clear. In-
spect primer elbows which attach to each cylinder head. Blow
compressed air through fittings to make sure passages are clear. Put
gasket sealing compound on primer elbow threads and reinstall elbows
in cylinder heads. Replace lines on distributor.
112
TM 9-1725
26-28 '
DISASSEMBLY, CLEANING, INSPECTION, REPAIR, AND
ASSEMBLY OF SUBASSEMBLIES
26. ASSEMBLY.
a. Install Oil Drain Tubes. Install each oil drain tube removed.
Place new rubber seal, washer, and packing nut on each end of tube
(fig. 104). Insert one end of tube in rocker box. Rotate tube to line
up other end with opening in other rocker box. Center tube between
rocker boxes. Push seals and washers into place and start packing
nuts carefully by hand (fig. 103). Be very careful not to cross the
threads. Tighten nuts (fig. 103) with spanner wrench.
b. Install Valves. Apply engine oil liberally to valve stems (fig.
108). Insert intake and exhaust valves in position in their respective
guides. While holding valves, place cylinder assembly on valve as-
sembly fixture or block. Make sure lower valve spring retaining
washer is in place in cylinder head. Install circlet on upper end of
both valve stems. Position three valve springs around each stem
with upper ends in retaining washer. Compress valve springs (par.
23 c). Insert split valve locks. Release spring compressor care-
fully. Install remainder of valves in same way.
c. Install Exhaust Elbows. Position elbow on cylinder mounting
flange studs, and install four washers and nuts. Tighten nuts securely,
and secure with lock. wire (fig. 99). Secure the two top nuts together
and the two bottom nuts together. Install exhaust elbows on remain-
ing cylinders. Place each cylinder assembly on clean bench, and
cover to protect it from dust until installed in engine.
Section V
PISTONS
Paragraph
Disassembly. . 27
Cleaning 28
Inspection and repair 29
Assembly 30
27. DISASSEMBLY.
a. Remove Piston Rings. Using piston ring tool, remove five pis-
ton rings from each piston (fig. 114). Unless rings are in unusually
good condition, replace them after piston inspection. As the piston
pin and articulated rod for each piston assembly was removed during
engine disassembly, all parts are now disassembled.
28. CLEANING.
a. Scrape carbon accumulations from piston heads, being careful
not to scratch piston. Polish piston skirt with crocus cloth to remove
113
TM 9-1725
28
ORDNANCE MAINTENANCE - ORDNANCE ENGINE
MODEL R975-C4 (CONTINENTAL)
RA PD 314863
Figure 110 — Cleaning Piston Ring Grooves with Ring Groove
Cleaner 4I-C-21 55
carbon and rough spots. Clean piston ring grooves with ring groove
cleaner (fig. 110), or fold piece of crocus cloth over double, then fold
again. Insert folded edge of crocus cloth in grooves, and run cloth
around grooves to polish carbon from them. Keep cloth wet. Re-
move carbon from oilholes in ring grooves. Clean out inside of pis-
114
TM 9-1725
28-29
ORDNANCE MAINTENANCE - ORDNANCE ENGINE
MODEL R975-C4 (CONTINENTAL)
Figure 1 13 — Measuring Piston Ring Gap Using Gage 4I-G-400
and Ring 4I-R-2492
Figure 1 14 — Installing Piston Rings Using Applier 4 1 -A-329-500
tons. Clean all other parts of assembly with dry-cleaning solvent, and
dry with air hose. Coat parts with lubricating oil.
29. INSPECTION AND REPAIR.
a. Pistons. Insert pistons for scores, cracks, and erosion. Re-
place heavily scored, cracked, or eroded pistons. Clean up light scores
with fine stone and polish piston surfaces with crocus cloth-and kero-
116
TM 9-1725
29-30
DISASSEMBLY, CLEANING, INSPECTION, REPAIR, AND
ASSEMBLY OF SUBASSEMBLIES
sene. Measure piston diameters 90 degrees from piston pin holes at
top and bottom of skirt and at top ring gland (fig. 111). Replace
piston if worn beyond allowable limits. The diameter of the piston
at the skirt should measure between 4.974 and 4.976 inches; and be-
tween 4.966 and 4.968 inches at the top ring gland.
Check piston ring grooves with new piston rings, and measure side
clearance with feeler gage (fig. 112). Replace piston if side clearance
exceeds allowable clearance for any ring groove. Side clearance for
the No. 1 (top) ring should measure between 0.005 and 0.007 inch,
loose fit; for the No. 2 ring, between 0.004 and 0.0055 inch, loose fit;
and for the Nos. 3, 4, and 5 rings between 0.0025 and 0.004 inch,
loose fit. Clean piston pin holes with crocus cloth. Inspect condition
of piston pin plugs, and replace worn plugs.
b. Piston Pins. Inspect piston pins for cracks, scores, straightness,
and flat spots. Replace cracked, bent, or badly scored pins. Clean up
slightly scored pins with fine stone. Measure diameter of pin with
micrometer. Replace pin if diameter is less than prescribed limit.
Piston pin diameters should measure between 1.2475 and 1.2480
inches.
c. Piston Rings. When piston has been removed, always install
new rings. Before installing rings in pistons, check ring fit in ring
gage, and measure gap with 5-inch feeler gage (fig. 113). Gap should
measure between 0.025 and 0.031 inch.
30. ASSEMBLY.
a. Install Piston Rings. Using piston ring compressor, install
piston rings. The top ring is marked “CHROME.” The two taper-
faced compression rings are marked “TOP 2 AND 3.” The two oil
control rings are marked “UP-Z,” and these two rings are interchange-
able. Install each ring in proper piston ring groove with the surface
marked “TOP” or “UP” towards piston head. After rings are installed
in each piston, check side clearance in groove. Place pistons on
clean bench in proper numerical order. The number of the cylinder
in which the piston is to be installed is stamped on the bottom of each
piston. The engine number is stamped at the top of each piston.
Section VI
CRANKSHAFT AND MASTER ROD
Disassembly
Cleaning
Inspection and repair
Assembly
Paragraph
31
. 32
33
. 34
117
TM 9-1725
31
ORDNANCE MAINTENANCE - ORDNANCE ENGINE
MODEL R975-C4 (CONTINENTAL)
118
Figure 115 — Crankshaft Assembly — Disassembled
i m 7- i / aw
ON, REPAIR, AND
IMBUES
RA PD 314860
ter Rod Assembly
Figure 1
RA PD 314716
figure 1 1 7 — Crankshaft Disassembly and Assembly
Fixture 41-5-4932
31. DISASSEMBLY.
a. Measure Bearing Journal. Before disassembling crankshaft
and master rod assembly, measure diameter of rear main bearing
journal with micrometer. Take measurement at this time to insure
119
TM 9-1725
31
ORDNANCE MAINTENANCE - ORDNANCE ENGINE
MODEL R975-C4 (CONTINENTAL)
RA PD 314715
Figure 1 18 — Checking Cap Screw Cotter Pin Hole
correct readings. Measure the journal at four points, and make a
note of diameter size, and out-of-round condition.
b. Remove Clamping Cap Screw. Clamp crankshaft and master
rod assembly into crankshaft assembly and disassembly stand
(41-S-4932) (fig. 117). Remove cotter pin from clamping cap screw
at rear of assembly. Insert pin punch into cotter pin hole to make
certain that all of cotter pin was removed, and that hole is entirely
clear (fig. 118). Using a wrench, remove clamping cap screw
(fig. 119). Lift off washers.
c. Remove Rear Crank. Install spreader through clamping cap
screw holes and spread rear crank (fig. 120). Slide rear crank as-
sembly off crankpin. Remove spreader, and reinstall cap screw
loosely so as not to damage threads.
(I. Remove Master Rod. Inspect surface of crankpin to make
sure that there are no nicks, burs, or any foreign- matter on the sur-
face, so as not to damage the master rod bearing when removing the
120
TM 9-1725
31
DISASSEMBLY, CLEANING, INSPECTION, REPAIR, AND
ASSEMBLY OF SUBASSEMBLIES
RA PD 314723
Figure 1 19 — Removing Clamping Cap Screw
REAR CRANK
RA PD 314697
Figure 120 — Spreading Rear Crank
121
TM 9-1725
31
ORDNANCE MAINTENANCE - ORDNANCE ENGINE
MODEL R975-C4 (CONTINENTAL)
RA PD 314683
Figure 122 — Front and Rear Crank Sections , Showing Plugs
122
TM 9-1725
31
DISASSEMBLY, CLEANING, INSPECTION, REPAIR, AND
ASSEMBLY OF SUBASSEMBLIES
i Figure 123 — Removing Rear Main Bearing Journal Plug
Figure 124 — Loosening Nuts Securing Rear Crank Stop Plate Bolts
rod (fig. 121). Clean off the crankpin, and if necessary, smooth up
nicks and burs with fine stone. Slide the master rod off the crank-
pin.
e. Remove Master Rod Spacer. Pour oil heated to 400°F., over
123
TM 9-1725
31
ORDNANCE MAINTENANCE - ORDNANCE ENGINE
MODEL R975-C4 (CONTINENTAL)
Figure 125 — Removing Crankpin Plug
master rod spacer on crankpin, and remove spacer (fig. 115).
f. Remove Rear Crank Plug. Using puller (41-P-2907-100), re-
move plug from rear main bearing journal in rear crank (figs. 122 and
123) and unscrew front plug in rear crank (fig. 115).
g. Remove Dynamic Damper. Remove cotter pins from two
nuts and bolts holding damper counterweight stop plate to rear crank.
Loosen and remove nuts (fig. 124). Turn crank over and lift out
stop plate. Slide damper counterweight up on crank until flanged
pins are opposite wider openings in crank. Push out flanged pins and
remove damper counterweight from crank.
h. Install Crankshaft Front End in Vise. Remove front crank
from assembly and disassembly stand. Place front crank counter-
weight in vise covered with soft brass jaws.
i. Remove Front Main Bearing Inner Race and Spacer. Remove
thread protector from front end of front crankshaft section. Remove
front main bearing inner race from crankshaft. Slip loose-fitted
bronze spacer from crankshaft.
124
TM 9-1725
31-33
DISASSEMBLY, CLEANING, INSPECTION, REPAIR, AND
ASSEMBLY OF SUBASSEMBLIES
Figure 126 — Staking Crankpin Plug
j. Remove Crankpin Plug from Crankpin. Using square wrench,
remove plug from rear of crankpin (fig. 125). Crankshaft disas-
sembly is now completed.
32. CLEANING.
a. Clean crankshaft front section carefully, and clean oil sludge and
residue from plug bore. Clean drilled oil passage in crankpin
thoroughly. Clean out bearing lubricating hole in front end of crank-
shaft, using a stiff wire. Clean rear crank, and clear out oil passage
in rear main bearing journal. Clean four oilholes to rear main bear-
ing, and oilhole to crankpin. Cover master rod bearing with pro-
tector, and clean master rod with dry-cleaning solvent As each part
is cleaned, coat it with a light film of lubricating oil and place it on
inspection bench.
33. INSPECTION AND REPAIR.
a. Crankshaft Front End. Have crankshaft sections magna-
fluxed. Inspect front section shaft threads and splines for nicks and
wear. Inspect crankshaft for cracks, nicks, scores, and galling. In-
spect thrust and front main bearing locations for galling. Note the
condition of the front crankcheek and extension. Check the front
counterweight for condition and tightness of rivets. Inspect crank-
125
TM 9-1725
33
ORDNANCE MAINTENANCE - ORDNANCE ENGINE
MODEL R975-C4 (CONTINENTAL)
Figure 127 — Master Rod
pin for any evidence of burning. Measure the diameter of the crank-
shaft front end and crankpin for size and out-of-round condition. Re-
place entire crankshaft assembly if crankshaft is cracked, or other-
wise damaged; if diameter is less than prescribed (Table of Limits),
or if it is out of round more than 0.002 inch. The crankshaft sec-
tions are assembled in balance. If one section is replaced, replace
other section also with a balanced assembly. If front end of crank-
shaft is out of round less than 0.002 inch, hone off high spots. If
shaft threads are badly worn or damaged, replace entire assembly.
Dress off rough spots with fine stone, and polish with crocus cloth.
Reinstall thread protector over threads. If condition of plug bore in
shaft and plug is satisfactory, reinstall plug. Tighten plug securely
and stake to crankpin in two places with prick punch (fig. 126).
b. Rear Crank. Have rear crank magnafluxed for cracks. Re-
place entire crankshaft assembly if rear crank is cracked, or badly
damaged. Inspect crank for scratches, nicks, and burs. Inspect in-
126
, RA PD 314873
Figure 128 — Pressing Out Slotted Master Rod Bearing
Using Plug 41 -P-2 11 5-500
side diameter of crankpin hole for scratches, burs, and chafing. Ex-
amine clamping cap screw hole threads for evidence of pulling.
Check condition of clamping cap screw threads. Remove light nicks
and burs with fine stone, and polish with crocus cloth. Dress threads
with fine stone. Inspect rear main bearing journal for roughness and
clearness of oil passages, and condition of the crankshaft gear retain-
ing screw hole threads. If out-of-round condition was discovered
when rear main bearing journal was measured (par. 31 a), remove
high spots with fine stone and polish with crocus cloth. Inspect crank-
cheek extension for condition. Replace entire assembly if any major
part is damaged. Freeze rear plug and reinstall in rear of rear main
bearing journal. Screw front plug into front of rear crank. Heat
master rod spacer in hot oil, and reinstall over crankpin with the
spacer radius against the crankpin radius.
c. Dynamic Damper. Magnaflux dynamic damper and damper
pins for cracks. Check pins for roughness, wear, condition of flanges,
and out-of-round condition. Replace cracked damper and unservice-
able pins. Inspect dynamic damper stop plate, stop plate bolts, and
nuts. Smooth off slight rough spots or burs. Replace badly damaged
parts.
d. Front Main Bearing. Using a magnifying glass, inspect front
bearing rollers for flat spots or pits. Replace roller assembly if rollers
127
TM 9-1725
33
ORDNANCE MAINTENANCE - ORDNANCE ENGINE
MODEL R975-C4 (CONTINENTAL)
are pitted or have flat spots. Place roller assembly on inner race, and
rotate roller Assembly to see that it turns smoothly in race. If assembly
does not rotate smoothly, replace roller assembly. Inspect inner bear-
ing race, and replace if damaged. Replace bronze bearing spacer if
it is warped or burred. Install bronze spacer and inner bearing race
on crankshaft. Place roller assembly in outer race. Wrap this as-
sembly in waxed paper and place on bench until needed when reas-
sembling engine.
e. Master Rod.
( 1 ) Master Rod. Magnaflux master rod for cracks. Inspect rod
for nicks, burs, and condition of kunckle pin holes and lock plate screw
holes. Replace rod if unserviceable condition is found.
(2) Master Rod Bearing. Check master rod bearing to see that
it is tight in rod. Inspect bearing surface for scores. With micrometer,
check inside diameter of bearing' at four equally spaced points. If
bearing is severly scored, if diameter exceeds 2.3137 inches, or if it is
out of round, replace bearing.
(3) Replace Master Rod Bearing.
(a) Remove Bearing. Drill out bearing locking pin. Slot bearing
with brooch, shaper, slotter, key seater, or mill. Tap out master rod
bearing with drift, or install collar and plug (41-P-2 1 15-500), and press
out in arbor press. The slots in the bearing will cause the bearing to
collapse and drop out of rod. Clean and polish master rod bore with
crocus cloth. Check inside diameter of master rod bore against out-
side diameter of replacement bearing. Refer to Table of Limits for
correct shrinkage. The importance of this fit cannot be overempha-
sized. Check dimensions at room' temperature.
(b) Install Bearing. Heat master rod to 450°F. Shrink new bear-
ing in dry ice or ice water, if ice is not available. Insert new bearing
in rod. Be sure that bearing oilholes line up with master rod oilholes.
Allow master rod to cool to room temperature.
(c) Install Locking Pin. Using a %-inch drill, drill through the
locking pin hole in master rod and through bearing. Tap locking pin
into place. Using a staking tool, peen master rod metal over locking
pin to secure the pin. Seal oilholes with paraffin to prevent metal
from entering oil passages.
(d) Ream Master Rod Bearing. Install knuckle pins and locating
pins in master rod (fig. 129). Install alining plugs in bearing and
piston pin bushing. Place master rod in alining and boring machine
(fig. 129). Insert alining bars through bearing and bushing holes to
aline holes. Secure master rod in machine. Remove alining bar
and the plug from the bearing bore, and install boring bar. Lock rod
in position and ream inside diameter of bearing. Bearing should have
an inside diameter of between 2.312 and 2.3137 inches. Remove
128
TM 9-1725
33
DISASSEMBLY, CLEANING, INSPECTION, REPAIR, AND
ASSEMBLY OF SUBASSEMBLIES
ALINING PLUG ALINING PLUG-i
^-locating pins
KNUCKLE PINS — ^
1. Master Rod with Knuckle Pins, Locating Pins, and Alining Plug Installed
2. Lining Up Bearing Hole in Boring Machine
miklc • _v RAPD 314875
3. Reaming Master Rod Bearing
Figure 129 — Reaming New Bearing in Master Rod Using
Fixture 4I-F-2987-425
TM 9-1725
33-34
ORDNANCE MAINTENANCE - ORDNANCE ENGINE
MODEL R975-C4 (CONTINENTAL)
master rod from machine. Remove plug from piston pin bushing.
Break all sharp edges from bearing. Remove paraffin from oilholes
and blow out oilholes with compressed air to clear passages.
(4) PISTON Pin Bushing. Examine piston pin bushing in master
rod to see that it is tight in rod and free from scores. Check diameter
with micrometer or plug gage. If bushing is loose, badly scored, or
worn beyond 1.2505 inches in diameter replace bushing.
(5) Replace Piston Pin Bushing.
(a) Remove Bushing. Insert small end of arbor press plug into
bushing. Place base of rod on arbor press table and insert collar in
base. Support rod over collar so that plug extends through bushing
and into collar. Press out old bushing. Remove plug and rod. Clean
up master rod bushing bore and remove all burs.
(b) Install Bushing. Place bushing on small end of plug and screw
cap on plug. Place end of rod over collar, and insert large end of plug
through rod bore so that it extends into collar. Locate split in bush-
ing in extreme end of rod at an angle of 45 degrees to the center line
of rod channel. Install rod in arbor press, and press down on plug
cap until the pressed-in plug bottoms against the collar. Remove the
plug and collar. Install rod in arbor press and press broaching bar
through bushing to expand it into rod.
(c) Ream Bushing. Place knuckle pins, locating pins, and alining
plug in master rod bearing. Plug in bushing and place master rod in
alining and boring machine. Install alining bars (fig. 129). Lock rod
into position in machine. Remove alining bar from newly installed
bushing, and install reaming fixture. Ream bushing to between 1.2495
and 1.2505 inches. Remove rod from machine. Remove plug from
bearing and knuckle pins and remove locating pins from master rod
flange.
(d) Spin Bushing Ends. Use spinning tool in drill press, and spin
over ends of master rod bushing until they bottom against chamfer at
each end of bushing. Ends of bushing should come flush with ends
of master rod.
(6) Check Master Rod Twist. Check master rod for alinement,
and for twist in relation to the crankpin (fig. 130), using alinement
stand (41-S-4977) and the proper sized alining bars (par. 92), a dial
indicator, and feeler gage set. Insert arbor in each knuckle pin hole
in master rod, one at a time. Check alinement of each hole. If mis-
alinement, twist of master rod, or misalinement of knuckle pin holes
exceeds 0.004 inch for every 6 inches, in any instance, replace rod.
Do not attempt to straighten master or articulated rods.
34. ASSEMBLY.
a. Install Dynamic Damper. Position dynamic damper with
“anti-prop” end facing up the same as rear crank rear main bearing
130
TM 9-1725
34
DISASSEMBLY, CLEANING, INSPECTION, REPAIR, AND
ASSEMBLY OF SUBASSEMBLIES
Figure 130 — Checking Master Rod Twist
Figure 131 — Installing Stop Plate
journal. Line up damper counterweight holes with rear crank exten-
sion holes. Insert counterweight pins. Center pins in counterweight
and install counterweight stop plate and bolts (fig. 131). Secure
plate in place by tightening two nuts securely on bolts. Secure nuts
with cotter pins.
131
TM 9-1725
34
ORDNANCE MAINTENANCE - ORDNANCE ENGINE
MODEL R975-C4 (CONTINENTAL)
THREAD LUBRICANT
32
Figure 135 — Measuring Clamping Cap Screw
b. Install Master Rod. Place front crankshaft section in assem-
bly stand. Make certain there is no foreign matter on crankpin.
Cover crankpin with oil and apply oil liberally to master rod bearing.
Slide master rod on crankpin with holes for knuckle pin locks facing
front, or flywheel end (fig. 121).
c. Install Rear Crank. Wipe all oil from the crankpin beyond
master rod flange. Remove clamping cap screw from rear crank.
Spread cheeks of rear crank (fig. 120). With counterweights lined
up as closely as possible, slide rear crank onto crankpin. Coat clamp-
ing cap screw with thread lubricant (fig. 132). Insert washer, screw
in crank, and tighten screw fingertight.
133
TM 9-1725
34
ORDNANCE MAINTENANCE - ORDNANCE ENGINE
MODEL R975-C4 (CONTINENTAL)
d. Check Master Rod End Play. With feeler gage, check end
play between master rod flange and master rod spacer (fig. 133).
The 0.017-inch feeler gage should fit between the flange and cheek;
the 0.019-inch feeler gage should not. Move rear crank to provide
proper amount of end play as indicated by feeler gages.
e. Line Up Cranks. From tool kit, select line-up bar that fits
alinement holes in cranks securely. Insert bar through alinement
holes in counterweight and dynamic damper (fig. 134). Remove
alining bar.
f. Measure Length of Clamping Cap Screw. Before tightening
rear crank cap screw which is now fingertight, measure the length of
the screw by placing the stretch measuring tool (41-T-3268) on cap
screw. Measure over tool with micrometer (fig. 135). Tighten cap
screw with wrench and wrench extension (fig. 119) until cap screw
is increased in length from 0.005 to 0.007 inch. The stretch is de-
termined by the length of the cap screw before and after tightening.
Check the alinement of the two crankshaft sections with the alining
bar at intervals while tightening the cap screw, and after screw is
tightened completely. Do not leave the bar through both counter-
weights while the screw is being tightened. Any movement of the
rear section will cause the bar to bend. When the two sections are
in line again, measure the end play of the master rod (fig. 133).
When end play is adjusted correctly, secure cap screw with cotter
pin (fig. 136). If the original cotter pin holes do not line up, drill a
new hole in cap screw. The new hole must be removed from all other
adjacent holes by at least Vi inch, center to center. If the specified
amount of stretch makes this impossible, reduce the thickness of the
cap screw washer as much as 0.010 inch by grinding from one side
or both sides of the washer. Grind carefully so that all points of the
washer will bear evenly on the cap screw head. After grinding, break
all sharp edges to within % 4 inch, and check for interference on the
fillet under the cap screw head. Install cotter pin from inside. Be
sure pin is pushed in as far as it will go (fig. 136). Cut cotter pin so
pin does not protrude more than Vi inch, and spread pin prongs around
circumference of rear crank.
g. Check Run-out of Shaft. Remove crankshaft assembly from
assembly stand and install on alinement fixture (fig. 137) or aline-
ment rollers (41-R-2660). Install dial indicator so that it contacts
smooth shaft surface between flywheel splines and extreme front end
threads. Rotate shaft one complete revolution. If run-out indication
on dial exceeds 0.004 inch, remove assembly from alinement fixture
and reinstall in assembly stand. Loosen clamping cap screw, and
recheck shaft alinement (subpar. f, above). Retighten clamping cap
screw. Again place assembly in alinement fixture, or rollers, and
134
DISASSEMBLY, CLEANING, INSPECTION, REPAIR, AND
ASSEMBLY OF SUBASSEMBLIES
RA PD 314702
Figure 136 — Installing Cotter Pinjor Clamping Cap Screw
MASTER ROD
CRANKSHAFT
RA PD 314855
Figure 137 — Crankshaft in Alinement Fixture
135
TM 9-1725
34-35
ORDNANCE MAINTENANCE - ORDNANCE ENGINE
MODEL R975-C4 (CONTINENTAL)
Figure 138 — Checking Crankshaft Run-out Using Rollers
41-R-2660 and Indicator 41-1-100
check run-out. If run-out is not within prescribed limits, replace en-
tire crankshaft assembly. If run-out is within prescribed limits, place
crankshaft assembly on bench, and cover to keep it clean until ready
to reinstall in engine.
Section VII
ARTICULATED RODS AND KNUCKLE PINS
Paragraph
Disassembly 35
Cleaning, inspection, and repair 36
Assembly 37
35. DISASSEMBLY.
a. Articulated rods and knuckle pins are already removed from
main crankcase assembly (par. 9 t).
136
TM 9-1725
35-36
DISASSEMBLY, CLEANING, INSPECTION, REPAIR, AND
ASSEMBLY OF SUBASSEMBLIES
RA PD 314717
Figure 139 — Checking Articulated Rod Bushing
36. CLEANING, INSPECTION, AND REPAIR.
a. Articulated Rods. Clean articulated rods with dry-cleaning
solvent, and coat with light film of engine oil. Have rods given a
magnaflux inspection for cracks. Inspect rods for nicks and burs.
Replace cracked or badly damaged rods. Remove slight burs or nicks
with fine stone. Examine knuckle pin and piston pin bushings for
scores and wear. Measure inside diameter of rod bushings with
micrometer or plug gage' (fig. 139). If bushings are greater in di-
ameter than noted below, replace bushings. Follow same procedure
to replace bushings (figs. 140 and 141) used to replace piston pin
bushings in master rod (par. 33 e (5) (a) and (c)). Both the
piston pin and knuckle pin bushings must be reamed at the same time
if both are replaced. Ream the piston pin bushing to a diameter
between 1.2495 and 1.2505 inches, and knuckle pin bushings to a
diameter between 0.8765 and 0.8772 inches. To permit bushing to
fit in master rod flange, cut off the ends. Insert cutting tool in drill
press spindle. Place rod in press and cut ends of bushing. Knuckle
pin bushings should measure from 1.378 to 1.382 inches in length,
and piston pin bushings from 1.448 to 1.452 inches. Place rods in
alinement stand (49-S-4977), and check for twist (par. 33 e (6)).
If any rod is out of alinement more than 0.004 inch in 6 inches, re-
place rod. Do not attempt to straighten rod. Match all articulated
rods in assembly for weight. Replace any rod weighing more or less
than weight specified in Table of Limits. Place rods on clean bench
in order. Rods are marked in I-section with weight, engine number,
and cylinder number. Use correct rod in each cylinder assembly.
137
TM 9-1725
36
ORDNANCE MAINTENANCE - ORDNANCE ENGINE
MODEL R975-C4 (CONTINENTAL)
3. Broaching Bushing RA PD 314868
Figure 1 40 — Replacing Articulated Rod Bushing Using •
Tool Set 41-T-3539-8
138
1. Alining Bushing Holes
2. Reaming Bushings RA PD 314871
Figure 1 41 — Reaming Articulated Rod Bushings Using
Fixture 41-F-2987-425
r ' : .
>&■ I 1
1 Jn M A
TM 9-1725
36-38
ORDNANCE MAINTENANCE - ORDNANCE ENGINE
MODEL R975-C4 (CONTINENTAL)
b. Knuckle Pins. Give knuckle pins magnaflux inspection for
cracks. Replace cracked pins. Inspect pins also for scores or rough-
ness. Smooth scored or scratched pins with a fine stone, and polish
with crocus cloth. Clean out knuckle pin oil passages. Examine
knuckle pin lock plates for burs, cracks, or warpage, and examine lock
plate screws for burred or damaged threads. Replace any unservice-
able parts.
37. ASSEMBLY.
a. Articulated rods and knuckle pins are not assembled at this
time. Place them on clean bench and cover them until ready to
install.
Section VIII
CRANKSHAFT GEAR ASSEMBLY
Paragraph
Disassembly 38
Cleaning, inspection, and repair 39
Assembly 40
38. DISASSEMBLY.
a. Remove spring retainer from crankshaft gear assembly. Pry
out each spring with its two pins. Turn hub within gear until gear lugs
are no longer engaged in hub slots. Separate hub and gear. Place
parts on bench for cleaning and inspection.
140
TM 9-1725
39-41
DISASSEMBLY, CLEANING, INSPECTION, REPAIR, AND
ASSEMBLY OF SUBASSEMBLIES
39. CLEANING, INSPECTION, AND REPAIR.
a. Clean assembly parts with dry-cleaning solvent, and coat with
light film of oil. Magnaflux gear for cracks. Inspect gear for burs
and broken or worn teeth; inspect for cracked or badly damaged gear.
Remove slight nicks and burs with fine stone, and polish with crocus
cloth. Examine hub and lugs for nicks and burs. Check condition
of screw holes in hub. Dress up nicks and rough spots. Smooth up
spring retainer if it is found to be rough. Check springs for con-
dition, and measure spring tension. Replace broken springs, or springs
which do not have at least 170 pounds of tension at a spring length
of 0.713 inch.
40. ASSEMBLY.
a. Assemble Crankshaft Gear. Insert hub in gear, and turn gear
until lugs are held in hub slots. Insert pins in end of each spring, and
push spring with pins into position (fig. 142). Place retainer on gear
assembly, alining cut-outs with screw holes. Place crankshaft gear
assembly on bench and cover to protect it from dust until reinstalled.
Section IX
DIFFUSER SECTION
Paragraph
Disassembly 41
Cleaning 42
Inspection and repair 43
Assembly 44
41. DISASSEMBLY.
a. Remove Idler Gears. Place diffuser section in fixture on bench
with impeller side down (fig. 143). Remove cotter pins from retain-
ing nuts securing idler gears to shaft. Remove in order, nuts, flat
washers, long bronze spacer, idler gears, and inner spacing washers
(fig. 144).
b. Remove Impeller Drive Gear Shaft Support. Remove cotter
pin from nut on impeller drive gear shaft, and cotter pins from nuts
holding shaft support to crankcase (fig. 145). Remove five nuts, one
from gear shaft, and four from gear shaft support. Lift support off
studs and shaft. Pull key out of top of impeller shaft. Shaft and gear
will remain with diffuser section. NOTE: It is important to remove
key at this time to prevent possibility of key dropping down with
the impeller drive gear into bearing after impeller has been removed.
141
TM 9-1725
41
ORDNANCE MAINTENANCE - ORDNANCE ENGINE
MODEL R975-C4 (CONTINENTAL)
c. Remove Impeller. Place mounting fixture block No. 2 (fig.
146) in jaws of vise. Mount diffuser section in fixture with impeller
up, and with nut on other end of impeller shaft seated properly in
fixture hexagonal recess. Remove circlip and lock from nut on
impeller shaft (fig. 147). Remove impeller retaining nut (fig. 148).
Install puller on impeller. Pull impeller from shaft (fig. 149).
d. Remove Impeller Drive Gear and Shaft. Push impeller drive
gear shaft up through diffuser section. At same time, hold drive gear
and bushing from below. Upper end of shaft, before removal, is
shown in figure 145. Remove diffuser section from fixture; turn
section over and reinstall on same fixture.
e. Remove Impeller Bearing Cage. With screwdriver, take out
seven slotted screws that hold impeller bearing cage to diffuser section
(fig. 150). Lift out cage assembly (fig. 151). Oil seals, rings, and
shims ordinarily will come out with cage. If they do not, remove
them from cage. Remove gasket
f. Disassemble Impeller Bearing Cage. Place fixture block No. 1
in vise with dowels pointing up (fig. 146). Mount cage assembly in
142
TM 9-1725
41
DISASSEMBLY, CLEANING, INSPECTION, REPAIR, AND
ASSEMBLY OF SUBASSEMBLIES
Figure 1 44 — Idler Gear Assembly — Disassembled
fixture with splined end of shaft in fixture spline and cage over two
dowels (fig. 152). Remove circlip and lock. Unscrew nut from im-
peller shaft. Remove large circlip holding thrust nut to bearing cage
(fig. 157). Using special wrench, remove thrust nut (fig. 152). Re-
move assembly from fixture. While holding cage, tap bearing thrust
nut end of shaft and drive out shaft (fig. 157). One thrust bearing
will come out with shaft. Using bearing puller, pull the other thrust
bearing off shaft. Push other thrust bearing out of cage.
g. Remove Impeller Oil Seal Cage. Cut and remove safety wires
from eight screws which hold oil seal cage to diffuser section. Remove
eight screws. Lift off cage, paper gasket, copper shim, and second
paper gasket (fig. 158). Remove the accessory drive shaft rubber
seals and spacers (fig. 200).
h. Remove Diffuser Ring. Remove two screws that hold dif-
fuser ring to diffuser section (fig. 160). Slide ring up and off bushings.
143
TM 9-1725
41-43
ORDNANCE MAINTENANCE - ORDNANCE ENGINE
MODEL R975-C4 (CONTINENTAL)
, \
IMPELLER DRIVE GEAR-/ KEY J SHAFT J RA PD 314738
\
Figure 145 — Removing Key from Impeller Driver Gear Shaft
FIXTURES FOR HOLDING DIFFUSER ASSEMBLY
NO.l NO.2
Figure 146 — Mounting Fixtures for Overhaul of Diffuser Section
42. CLEANING.
a. Clean all parts in dry-cleaning solvent, and coat with lubricating
oil. Blow out all the oil passages in section to make sure they are
clear. Clean all oilholes leading to bushings with compressed air.
43. INSPECTION AND REPAIR.
a. Inspect Diffuser Section. Check entire section for cracks or
other indications of damage (fig. 153). Check points where pullers
are attached during removal, to see that pullers have not damaged
section. Check machined flanges at rim and bearing cages for
scratches, burs, or roughness. Smooth scratches, burs, or rough spots
144
TM 9-1725
43
DISASSEMBLY, CLEANING, INSPECTION, REPAIR, AND
ASSEMBLY OF SUBASSEMBLIES
Figure 148 — Removing Impeller Shaft Nut
with fine stone, and polish with crocus cloth. Inspect all studs for
tightness and thread condition. Replace any unserviceable part.
Idler gear studs are removed by inserting a square drive in stud head
and unscrewing studs. Inspect inner surfaces of accessory and starter
145
IMPELLER DRIVE GEAR OPENING A L IMPELLER SHAFT RA PD 314761
RA PD 314733
Figure J52 — Removing Impeller Cage Thrust Nut
shaft bushings for smoothness, freedom from scratches and scores, and
condition of oil grooves. Check inside diameter of bushings with
micrometers or plug gages (fig. 154). If bushings are worn beyond
maximum permissible diameters, replace bushings.
The diameter of the starter shaft bushing in the diffuser section
should measure between 1.3745 and 1.3755 inches. The accessory
TM 9-1725
43
DISASSEMBLY, CLEANING, INSPECTION, REPAIR, AND
ASSEMBLY OF SUBASSEMBLIES
Figure 1 55 — Line Reaming Starter Shaft Bushings
drive shaft bushings in the diffuser section should measure between
0.7395 and 0.7405 inches.
b. Replace Diffuser Section Bushings.
(1) If bushing in diffuser section is replaced, replace correspond-
ing bushing in rear crankcase section.
(2) Remove Starter Shaft Bushings. Tap out bushing lock-
ing pins in both diffuser and rear crankcase sections. Drill out bush-
ings until a shell approximately 0.015 inch thick remains. Break out
remaining shells. Clean up bushing bores.
(3) Install Bushings. Heat diffuser and rear crankcase sections
to 300°F., and shrink replacement bushings. Press new bushings into
bushing bores. Make sure bushing flanges bottom against bosses in
diffuser and rear crankcase sections. Using pilot on drill, bore locking
pin holes. Install locking pins. Drill oilholes through bushings to
line up with oil passages.
(4) Ream Bushings. Assemble diffuser section to rear crank-
case section. Mount sections in vise, and install alining fixture sup-
ports (41-F-2987-2 10) in crankcase sections. Install reamer and
alining bar (41-R-2324) through bushing holes, and install alining
fixture supports through starter gear opening in rear crankcase sec-
tion (fig. 155). Line ream bushings to limits specified (subpar. a
above). Remove reamer, alining bar, and support fixtures.
(5) Check End Clearance. Install starter gear and check end
clearance of gear. If clearance is less than 0.050 inch, cut bushing
end flange to provide end clearance between 0.013 and 0.045 inch
149
TM 9-1725
43
ORDNANCE MAINTENANCE - ORDNANCE ENGINE
MODEL R975-C4 (CONTINENTAL)
ALINEMENT FIXTURE No. 41-F-2987-210 -A RA PD 314883
Figure 156 — Line Reaming Accessory Drive Shaft Bushings
loose fit. Remove starter gear. Remove diffuser and rear crankcase
sections from vise. Separate cases. Break all sharp edges from
bushings, and polish with crocus cloth.
(6) Replace Accessory Drive Shaft Bushings. Follow the
procedure specified (subpar. (1) above), for replacing starter shaft
bushings. If either accessory drive shaft bushing in the diffuser or
rear crankcase section, is replaced, corresponding bushing in rear
cranRcase section, or diffuser must be replaced. After bushings are
installed, remove headless screw and plug from bushing boss in diffuser
section. Screw bushing drill tool into oil pressure passage. Drill oil-
hole through bushing. Remove tool and clean holes. Assemble cases;
place them in vise covered with soft brass jaws, and line ream bush-
ings to limits specified (subpar. a, above). Attach support fixture
(41-F-2987-2 10) to accessory drive shaft opening in rear crankcase
section. Install reamer (41-R-390), and line ream bushings in both
crankcase sections. After reaming bushings, remove support fixture,
separate cases, break all sharp edges from bushings, and polish with
crocus cloth. Bur and clean out oil passages. Install new lead plug
and headless screw in bushing boss in diffuser section. Stake screw.
(7) Replace Idler Gear Bushing. NOTE: It is seldom neces-
sary to replace idler gear bushings as they are subjected to little wear.
Aside from cleaning, they require no servicing. Screw stud out of
150
TM 9-1725
43
DISASSEMBLY, CLEANING, INSPECTION, REPAIR, AND
ASSEMBLY OF SUBASSEMBLIES
RA PD 314745
Figure 157 — Impeller Bearing Cage — Disassembled
impeller side of diffuser section with square drive. Turn drive bar
counterclockwise. Bore out bushing until shell approximately 0.015
inch thick remains. Break out remaining shell and be careful idler
gear stud threads are not damaged in the procedure. Clean up bush-
ing bore. Check inside diameter of bore with outside diameter of
bushing to be installed. Select fit within prescribed limits of 0.001 to
0.003 inch. Heat diffuser section, and press new bushing into place.
Using fixture and reamer, ream bushing, being careful not to strike
bottom of bore. The bushing diameter should measure between
0.9995 and 1.0005 inches. Remove reamer and fixture, and break all
sharp edges. Apply gasket compound to the head of threads of idler
gear stud and replace stud. Tighten stud securely.
c. Diffuser Ring. Inspect diffuser ring (fig. 158) for cracks, burs,
or warpage. Remove slight burs with fine stone. Replace cracked
or warped ring.
d. Impeller. Check impeller on a surface plate for warpage.
Inspect it also for bent or broken blades, or other indications of dam-
age (fig. 158). Inspect condition of splines. Replace impeller if
damage is found.
e. Oil Seal Cage. (fig. 158). Inspect inside diameter of cone very
closely for scores, scratches, or any indication of roughness. Check
151
TM 9-1725
43
ORDNANCE MAINTENANCE - ORDNANCE ENGINE
MODEL R975-C4 (CONTINENTAL)
152
Figure 1 58 — Impeller, Diffuser Ring, and Oil Cage — Disassembled
1 RA PD 314743
Figure 1 59 — Oil Seal Cage Flange
outside diameter and flange surfaces for smoothness. Check for
evidence of oil seal ring wear and scoring on smallest inside diameter.
Replace cage if any surface is found to be damaged.
f. Impeller Shaft Assembly (fig. 157). Clean bearings thor-
oughly in dry-cleaning solvent. Dry them with compressed air blown
through the races, but be careful not to spin bearing races. Oil bear-
ings, and rotate them by hand to check for flat spots, roughness, or
damage. Replace bearings if damaged. Inspect shaft and gear as-
sembly by the magnaflux method for cracks, for condition of splines,
threads, and gear teeth. Replace shaft and gear assembly if any
damage is apparent. Inspect bearing cage for cracks or other evi-
dence of damage. Inspect condition of thrust nut. Replace any
unserviceable parts.
g. Impeller Drive Gear Assembly (fig. 163). Inspect drive gear
support for cracks and for general condition. Inspect shaft for scores,
TM 9-1725
43
DISASSEMBLY, CLEANING, INSPECTION, REPAIR, AND
ASSEMBLY OF SUBASSEMBLIES
FLANGED SURFACE
MATCHING SURFACE
153
TM 9-1725
43
ORDNANCE MAINTENANCE - ORDNANCE ENGINE
MODEL R975-C4 (CONTINENTAL)
OIL SEAL CAGE
WIRED SCREWS
STAKED SCREWS
DIFFUSER RING - c -CS'
RA PD 314746
Figure 160 — Staked Screws for Diffuser Ring
burs, or out-of-round condition. Inspect gear by magnaflux method
for broken, worn, or damaged teeth. Replace gear support, drive
shaft, or gear, if they are unserviceable. Check gear bushing very
carefully for scores, scratches, burs, or roughness, and for good con-
dition of oil grooves. If any of these conditions exist, replace gear.
Measure inside diameter with telescopic micrometer. If inside di-
ameter is worn beyond permissible limits, replace gear. The diameter
should be between 1.1250 and 1.1255 inches. Inspect bearing journal
very carefully for scores, scratches, roughness, wear, or out-of-round
condition. Replace bearing if any of these conditions are found.
Check bearing diameter with micrometer. If diameter exceeds al-
lowable limits (Table of Limits) replace bearing. Diameter should
measure between 1.220 and 1.1215 inches.
h. Idler Gear Assembly (fig. 144). Inspect idler gear by magna-
flux method for broken, cracked, or worn teeth. Inspect thrust
washers for scores, burs, roughness, or wear. Replace any unservice-
able parts.
i. Accessory Drive Gears. Inspect gears by magnaflux method
for cracks, broken teeth, scores, or wear. Replace gears if any un-
serviceable parts are found.
154
TM 9-1725
43
DISASSEMBLY, CLEANING, INSPECTION, REPAIR, AND
ASSEMBLY OF SUBASSEMBLIES
RA PD 314741
Figure 161 — Installing Lock in Impeller Drive Shaft
IMPELLER BEARING'
CAGE
STAKED SCREWS
IMPELLER' DRIVE GEAR
SHAFT OPENING — 1 — '
RA S»0 314752
Figure 162 — Staking Impeller Bearing Cage Screws
155
TM 9-1725
43-44
ORDNANCE MAINTENANCE - ORDNANCE ENGINE
MODEL R975-C4 (CONTINENTAL)
Figure 1 63 — Impeller Drive Gear — Disassembled
Figure 1 64 — Positioning Impeller Drive Gear
44. ASSEMBLY.
a. Install Oil Seal Cage. Lap the flanged surface on cage to the
matching surface on the diffuser section to insure a perfect contact
between the two surfaces (fig. 159). Make sure all lapping com-
pound is removed after this operation. Install in order, new paper
gasket, copper shim, another new paper gasket, then the cage
(fig. 158). Mounting holes for installing these parts are unequally
spaced to insure correct installation. Install and tighten eight attach-
156
TM 9-1725
44
DISASSEMBLY, CLEANING, INSPECTION, REPAIR, AND
ASSEMBLY OF SUBASSEMBLIES
Figure 165 — Checking End Play in Impeller Drive Gear Shaft
Figure 166 — Oiling Between Impeller Drive Shaft and
Oil Seal Cage
ing screws. Wire them together in groups of three, three, and two
(fig. 160 ).
b. Install Diffuser Ring. Slide diffuser ring in place over bush-
ings in diffuser section. Be sure that the ring is installed all the
157
TM 9-1725
44
ORDNANCE MAINTENANCE - ORDNANCE ENGINE
MODEL R975-C4 (CONTINENTAL)
Thick flanged steel spacer— \
Figure 167 — Oil Seal Rings — Disassembled
way, and makes good contact with diffuser section. Install and tighten
two mounting screws, and stake the ring to the slot in the screws.
c. Assemble Impeller Bearing Cage. Using an arbor press, press
impeller bearing on splined end of impeller shaft. Place side marked
“GEAR SIDE” towards gear (fig. 157). Place shaft with bearing in
bearing cage. Position assembly in fixture block No. 1 with splined
end of shaft in fixture. Place upper bearing over shaft and into cage.
Place end of bearing marked “GEAR SIDE”, down. Tap bearing into
place with soft hammer if necessary. Install bearing retaining nut,
and tighten with special wrench. Install shaft nut, and tighten se-
curely to 1,100 to 1,200 inch-pounds of torque. Using tool (41-T-
3217-100), install old lock in shaft nut (fig. 161).
d. Install Bearing Cage. Place diffuser section in fixture with
front side of section up. Using a new gasket, position cage and gear
assembly over gasket on front side of diffuser section. Have gear
teeth opening in cage face impeller drive gear shaft opening (fig. 162).
Install seven slotted screws that hold cage to diffuser section. Tighten
screws securely with screwdriver. Stake screws to slot in cage
(fig. 162).
e. Install Impeller Drive Gear (fig. 163). Lubricate all parts
thoroughly before assembling. Place bearing in impeller drive gear
(flanged side down). Position gear and bearing over shaft opening,
with keyway pointed exactly toward impeller shaft (fig. 164). Push
shaft up from under side of diffuser section. Line up shaft keyway
with bearing keyway. Place key in position in two keyways. Put
support over gear and shaft, making sure that shaft and journal are
158
SCREWS HA pd 314734
Figure 168 — Diffuser Section with Oil Rings Installed
positioned so that key enters support keyway. Do not drive support
into place. Install shaft nut on end of shaft. Tighten nut finger-
tight. Install four washers and nuts on studs that hold support to
diffuser section. Tighten shaft nut to 1,100 to 1,200 inch-pounds of
torque. Check gear operation by rotating gear through one complete
revolution. The gear must run freely. If the gear does not operate
freely, it indicates improper assembly of impeller shaft, damaged
bushings, or improperly machined bushings. If gear does not operate
freely, disassemble impeller gear drive and- inspect bushings. Re-
place damaged or improperly machined bushings. Reassemble gear
drive. Again check gear operation. If it does not operate freely, and
proper assembly has been made, remove and replace the assembly.
When a check of the gear operation shows that the gear is operating
freely, raise the gear with your fingers to see that it has slight end
play (fig. 165). When assembly is complete, tighten and secure the
four nuts on the diffuser section studs with cotter pins. Put a cotter
pin through nut on end of impeller shaft and fasten it securely.
159
TM 9-1725
44
ORDNANCE MAINTENANCE - ORDNANCE ENGINE
MODEL R975-C4 (CONTINENTAL)
RA PD 314764
Figure 169 — Tightening Impeller Retaining Nut Using
Wrench 41 -W -3631
RA PD 314748
Figure 170 — Checking Impeller End Play Using Gage 41-G-400
f. Install Oil Rings. Place diffuser section with impeller side up
in special mounting block No. 2. Squirt a liberal amount of engine
oil between impeller drive shaft and oil seal cage (fig. 166). Install
thick-flanged steel spacer with large diameter down, over shaft and
in oil cage (fig. 167). Next, install, in order, over shaft, new bronze
oil ring, thin-flanged steel spacer with large diameter down, another
160
TM 9-1725
44
DISASSEMBLY, CLEANING, INSPECTION, REPAIR, AND
ASSEMBLY OF SUBASSEMBLIES
RA PD 314751
Figure 171 — Installing Idler Gear Spacer
new bronze oil ring, a second thin-flanged steel spacer with large
diameter down, a third bronze oil ring, and finally, a plain flat washer
(0.035 inch thick), and the same number of 0.010-inch spacers as
were removed in disassembly. Figure 168 shows diffuser section
with oil rings installed.
g. Install Impeller. Slide impeller down over splined end of shaft.
Tap impeller down as close as possible to hub with soft hammer.
Install retaining nut, and tighten it from 1,100 to 1,200 inch-pounds of
torque (fig. 169).
li. Check Impeller Clearance. With feeler gage (fig. 170), check
clearance between face of impeller and face o of diffuser section at
several points around the circumferences. Clearance should be be-
tween 0.020 and 0.030 inch. If clearance is greater than 0.030 inch,
remove a sufficient number of 0.010-inch shims from the impeller
shaft to bring the clearance within the prescribed limits. If the clear-
ance is less than 0.020 inch, install the necessary number of 0.010-inch
shims to the impeller shaft to bring the clearance within the prescribed
limits. To change the number of shims on impeller shaft, remove
shaft nut, pull impeller from shaft, and change the number of shims
as required. Reinstall impeller and shaft nut. Tighten nut to from
1,100 to 1,200 inch-pounds of torque. Recheck clearance to make
161
TM 9-1725
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ORDNANCE MAINTENANCE - ORDNANCE ENGINE
MODEL R975-C4 (CONTINENTAL)
sure that it falls within allowable limits. If it does not, repeat pro-
cedure again, and readjust until clearance is within limits, and im-
peller retaining nut is installed and tightened to the proper tension.
Install lock in shaft and nut slot. Secure lock in place by installing
circlip in nut (fig. 158).
i. Replace Lock at Rear of Impeller Shaft. Lift diffuser section
from mounting block, and with impeller side down, reinstall in fixture.
Remove old lock from nut at bearing cage end of impeller shaft.
Install new lock (fig. 161) using a special tool. The old lock will be
battered by the force applied when the impeller was installed. Install
new circlip in nut (fig. 157).
j. Install Idler Gears. Lubricate idler gears and bushings. Install
inner spacer over idler gear stud. Then, in order, install gear, long
bronze spacer with bell end down (fig. 171), flat washer, nut, and
cotter pin. Install other idler gear in same way. With fingers, check
gears for perceptible end play and for free rotation. Check impeller
drive and idler gears for end play with feeler gage set. End play
for accessory idler gears should be from 0.011 to 0.050 inch. If gears
do not have the proper amount of end play, and/or, do not rotate
freely, check idler gear studs to make sure they have been driven to
the proper depth. Check the spacer under the idler gear to make sure
the correct spacer has been used. When proper adjustments have
been obtained, place diffuser section assembly on bench. Cover
assembly for protection from dirt and dust until ready to reinstall
in engine.
Section X
REAR CRANKCASE SECTION
Paragraph
Disassembly 45
Cleaning * 46
Inspection and repair 47
Assembly 48
45. DISASSEMBLY.
a. Remove Cover Plates. Remove two nuts tightened finger-
tight, and remove cover plates installed on starter and generator
openings when starter and generator were removed (fig. 35).
b. Remove Carburetor Elbow. Cut and remove safety wires from
four nuts securing carburetor inlet elbow to rear crankcase section
162
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DISASSEMBLY, CLEANING, INSPECTION, REPAIR, AND
ASSEMBLY OF SUBASSEMBLIES
Figure 172 — Removing Retaining Nuts from Inside of
Three-way Drive Housing
Figure 173 — Tachometer Drive Mounting
(fig. 35). Remove nuts and flat washers from mounting studs, and
lift elbow off studs.
c. Remove Three-way Accessory Drive Housing. Cut and remove
safety wires from nuts holding right cover on three-way drive hous-
ing (fig. 35). Remove four nuts and take off cover from studs. Re-
move cotter pins from two retaining nuts inside three-way drive
housing. Remove nuts (fig. 172). Cut and remove safety wires
163
ORDNANCE MAINTENANCE - ORDNANCE ENGINE
MODEL R975-C4 (CONTINENTAL)
RA PD 314846
Figure 174 — Removing Tachometer and Three-way
Accessory Drive
Figure 175 — Removing Oil Pump Attaching Nuts Using
Wrench 4 1 -W- 1 577-500
164
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45
IDLER GEAR SHAFT FLANGE RA PD 314843
Figure 176 — Pulling Generator Idler Gear Shaft
DISASSEMBLY, CLEANING, INSPECTION, REPAIR, AND
ASSEMBLY OF SUBASSEMBLIES
PULLER
Figure 177 — Removing Generator Idler Gear Shaft
from three external mounting nuts which attach three-way housing
to crankcase. Remove nuts and flat washers, and lift off three-way
housing from crankcase studs. Pull three-way accessory drive gear
from vacuum and fuel pump drive shaft in three-way housing.
165
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ORDNANCE MAINTENANCE - ORDNANCE ENGINE
MODEL R975-C4 (CONTINENTAL)
IDLER GEAR
SEAL
PULLER, TOOL NO. 41-P-2951-11
RA PD 314857
Figure 179 — Removing Magneto Drive Oil Seals
d. Remove Tachometer Drive Assembly. Cut and remove safety
wires from three nuts holding tachometer drive assembly to rear
crankcase section. Remove nuts and flat washers. Pull assembly
166
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DISASSEMBLY, CLEANING, INSPECTION, REPAIR, AND
ASSEMBLY OF SUBASSEMBLIES
RA PD 314847
Figure 1 80 — Removing Accessory Drive Shaft
straight off studs. Do not remove six screws holding tachometer drive
side cover in place.
e. Remove Tachometer and Three-way Accessory Drive. Cut
and remove safety wires from three nuts holding drive gear assembly
to rear crankcase section. Remove nuts and flat washers. Remove
drive gear assembly from crankcase (fig. 174). If necessary, place
wood block on gear, and drive the assembly from crankcase through
opening.
f. Remove Oil Pump. Remove safety wires from five nuts, and
remove cotter pins from the remaining three nuts. Remove the eight
oil pump attaching nuts. Use special wrench (41-W-1577-500) to
remove several of these nuts (fig. 175). Remove pump by pulling
it straight off studs. Pump drive gear comes off with the pump. Re-
move gear from pump at once to avoid dropping it.
g. Remove Generator Idler Gear. Cut and remove safety wires
from plugs and from nuts on idler gear shaft flange. Remove nuts
from studs. Remove plug from center of flange and insert puller.
Pull shaft from crankcase by sliding weight on puller (fig. 176).
Reach in through starter opening, remove shaft (fig. 177), and pull
gear through opening, lining up edges of gear with»slots in opening
(fig. 178).
h. Remove Accessory Drive Shafts. Remove retaining screws
which hold the magneto drive oil seals in position in rear crankcase
section. Install puller (41-P-2951-11) on one of the seals. Hook
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ORDNANCE MAINTENANCE - ORDNANCE ENGINE
MODEL R975-C4 (CONTINENTAL)
ACCESSORY GENERATOR STARTER
DRIVE HOUSING IDLER GEAR DRIVE / — GENERATOR
OIL PUMP ^-CARBURETOR ^-TACHOMETER AND '—THREE-WAY
MOUNTING ELBOW THREE-WAY ACCESSORY DRIVE HOUSING
PAD MOUNTING PAD DRIVE OPENING OPENING
RA PD 314845
Figure 181 — Rear Crankcase Section Stripped
puller under the flange, and pull seal from crankcase (fig. 179). Lift
shaft from bushing in crankcase (fig. 180). Repeat procedure for
other seal and shaft.
i. Remove Starter Shaft Seal. Place drift of suitable size against
inner surface of starter shaft seal housing which is positioned against
starter shaft bushing. Drive seal out through front of rear crankcase
section.
j. Remove Rear Crankcase Section. Remove self-locking nuts
and bolts securing crankcase section to engine assembly stand. Lift
off crankcase section; place it on bench for cleaning and inspection.
46. CLEANING.
a. Steam-clean case and wash with dry-cleaning solvent to remove
grease and dirt. Coat machined surfaces with light film of oil. Re-
168
BUSHING
PLUG GAGE
DISASSEMBLY, CLEANING, INSPECTION, REPAIR, AND
ASSEMBLY OF SUBASSEMBLIES
' ** L
ACCESSORY DRIVE SHAFT BUSHING
RA PD 314781
STARTER GEAR
TM 9-1725
46-47
1 82 — Checking Starter Gear Bushing
move any gasket material or sealing compound that may still be
adhering to parting flanges.
47. INSPECTION AND REPAIR.
a. Rear Crankcase Section. Inspect casting very carefully for
cracks and other indications of damage, particularly fuel induction
tube connections and webs. Replace entire crankcase if casting is
cracked or damaged. Inspect all flanges and machined surfaces. In-
spect all mounting pads for nicks, burs, or roughness. Remove nicks
or burs with a fine stone, and polish with crocus cloth. Check all
studs for tightness and condition of threads. Replace studs if neces-
sary (par. 13 f).
b. Bushings. Inspect starter gear and accessory drive shaft bush-
ings for nicks, scores, or other damage. If bushings are in good con-
dition, check their diameter (fig. 182). If bushings are damaged, or
worn beyond allowable limits (1.3745 and 1.3755 inches for the
starter shaft bushing and 0.7495 and 0.7505 inch for accessory drive
169
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MODEL R975-C4 (CONTINENTAL)
Figure 1 83 — Oil Plugs in Rear Section
shaft bushings), replace bushing, and replace matching bushing in
diffuser section. Follow procedure prescribed in paragraph 43 b
subpars. (1) through (6). NOTE: It is not necessary to drill out,
or remove, pin from accessory drive-shaft bushings in the rear crank-
case section, as these have slotted keyways. Line up slot with key and
install bushing.
c. Clean Oil Lines.
(1) Remove No. 1 Oil Line Plug (fig. 183). Plug oilhole to
oil standpipe. Insert nozzle of compressed air hose in oil line plug
opening, and blow out line. Make certain air passes through opening
to generator idler gear shaft.
(2) Plug Generator Idler Gear Shaft Opening. Blow out
oil line to oil standpipe opening in front of rear crankcase section
through the No. 2 plug opening (fig. 183).
(3) Plug Standpipe Opening. With air hose in same place, plug
standpipe and generator idler gear shaft openings. Blow air through
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DISASSEMBLY, CLEANING, INSPECTION, REPAIR, AND
ASSEMBLY OF SUBASSEMBLIES
openings to see that line to oil pump opening is clean. Reinstall plug
No. 1.
(4) Remove Oil Line Plug No. 2. Blow through oil line to
generator idler gear shaft opening. Blow air through generator idler
gear shaft opening to make sure line to generator drive gear shaft
opening support pad is clear. From generator drive gear support
pad opening, blow through opening for three-way housing.
(5) Remove No. 3 Oil Line Plug. Blow through opening to
sump drain to make sure sump connection is clear.
48. ASSEMBLY.
a. No subassemblies are installed in rear crankcase section at this
time. Refer to chapter 5.
Section XI
OIL PUMP
Paragraph
Disassembly 49
Cleaning 50
Inspection and repair 51
Assembly 52
Tests and adjustments 53
49. DISASSEMBLY.
a. Remove Oil Pump Drive Gear. Oil pump drive gear is
splined to pressure pump drive shaft. Lift drive gear from top of
pressure pump body. Place gear, and all other parts subsequently re-
moved, on bench ready for cleaning and inspection.
b. Remove Pressure Pump Body. Cut lock wire securing two
pairs of body attaching screws, and remove screws. Lift pressure
pump body off pump drive shafts. Lay pressure pump body on side
on bench, being careful not to mar or scratch the lapped mounting
surface on underside of body.
c. Remove Gear Spacer Plate. Using both hands, lift off gear
spacer plate. Do not pry spacer plate loose from scavenger pump
body with tool, or the lapped matching surfaces of the spacer plate
and the scavenger pump body may be damaged. Pressure pump
drive shafts, drive and driven gears, and the scavenger pump drive
gear will come out when the spacer plate is removed. The scavenger
pump driven gear may come out with the spacer plate. If it does not,
remove by lifting it out of scavenger pump body. The scavenger
pump drive gear is keyed to the pressure; pump driven shaft. If it
171
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ORDNANCE MAINTENANCE - ORDNANCE ENGINE
MODEL R975-C4 (CONTINENTAL)
OIL PUMP DRIVE GEAR
-PRESSURE PUMP BODY ATTACHING
SCREWS
PRESSURE PUMP-
BODY
PRESSURE PUMP-
DRIVEN GEAR
PRESSURE PUMP-
DRIVEN SHAFT
WOODRUFF — ^
KEYS
SCAVENGER PUMP
DRIVEN GEAR a
PRESSURE PUMP DRIVE GEAR
-PRESSURE PUMP DRIVE SHAFT
• GEAR SPACER PLATE
SCAVENGER PUMP DRIVE GEAR
SCAVENGER -
BODY PLUG
GOVERNOR
DRIVE
GEAR
'Ik:
to i
C—- -
PRESSURE BODY PINS
SCAVENGER PUMP BODY
OIL PUMP MOUNTING STUDS
OIL INLET STRAINER
STRAINER SPRING
PUMP BODY
TO COVER
STUD JL
GASKET — "T ^
COVER
PAL NUT-t^^s
Will
OIL THERMOMETER
, ADAPTER GASKET
SPRING \
PLUNGER
•L WASHER
STUD NUT/
GOVERNOR DRIVE —
INTERMEDIATE GEAR
/ L RELIEF VALVE BALL V \ \ \
RELIEF VALVE SPRING^ \ \
RELIEF VALVE — M ’
ADJUSTING SCREW \
RELIEF VALVE BODY WASHERS-^
RELIEF VALVE CAP
OIL THERMOMETER ADAPTER
RA PD 314852
Figure 1 84 — Oil Pump — Disassembled
TM 9-1725
49-50
DISASSEMBLY, CLEANING, INSPECTION, REPAIR, AND
ASSEMBLY OF SUBASSEMBLIES
cannot be removed from the shaft easily, turn the spacer plate upside
down. Tap end of oil pressure pump driven shaft to break the oil
pump driven gear away from the Woodruff keys which lock it to the
shaft. Do not attempt to pry it off with tools. Remove the gear by
placing fingers between spacer plate and top of gear, being sure not to
mar or scratch the lapped surface of spacer plate. After gear is re-
moved, pull Woodruff keys from driven shaft key way with pliers,
and remove scavenger pump drive gear from shaft.
cl. Remove Scavenger Pump Body Cover. Turn scavenger
body over on bench, being careful not to bend pressure pump body
pins or to mar lapped surface of scavenger pump body. Remove three
palnuts, stud nuts, and washers, which attach scavenger pump body
cover to scavenger body. Lift off cover. Remove gasket, and dis-
card it if new gasket is available.
e. Remove Governor Drive Intermediate Gear. As drive shaft
to which governor drive intermediate gear is splined has previously
been removed, remove intermediate gear by lifting it from scavenger
pump body.
f. Remove Governor Drive Gear. Withdraw governor drive gear
through the rear of the scavenger pump body.
g. Remove Relief Valve Assembly. Cut safety wire from relief
valve aluminum cap, and remove cap using wrench (41-W-1577-400).
Remove gasket and flat washer. Unscrew and remove lock nut.
Remove second flat washer. With screwdriver, remove relief valve
adjusting screw. Remove relief valve spring with fingers. Ball and
plunger may come out with spring. With the other end of special
wrench, unscrew and remove relief valve body. If ball and plunger
did not come out when spring was removed, remove them now from
the relief valve body. Remove relief valve body gasket.
h. Remove Oil Pump Thermometer Adapter. Unscrew oil
pump thermometer adapter from scavenger pump body and remove
it. Remove and discard gasket from adapter, and pull out spring
from inlet strainer.
i. Remove Oil Inlet Strainer. Insert finger inside inlet strainer,
and pull strainer from scavenger pump opening. The oil pump is
now disassembled.
50. CLEANING.
a. Wash all oil pump parts thoroughly in dry-cleaning solvent.
Dry parts with air hose. Cover parts with light coat of engine oil
to prevent them from rusting. Remove Vi-inch plug at rear of
scavenger pump body. Blow out all passages in scavenger pump
body with compressed air. Replace Vi-inch plug as soon as passages
are clean.
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MODEL R975-C4 (CONTINENTAL)
51. INSPECTION AND REPAIR.
a. Pressure Pump Body. Handle pump body with the extreme
care to prevent damage to lapped surface. Inspect drive and driven
gear bores for heavy scratches or scoring. If bores are badly
scratched or scored, replace pressure pump body, gear spacer plate,
and scavenger pump body. This assembly is doweled with master
dummy gears by the manufacturer, and none of the three parts are
interchangeable. If at any time it is found necessary to replace any
one of these parts, replace all three in matched sets. Measure clear-
ance betwen the shaft bore and shafts. If either clearance between
the shafts and shaft bores exceeds 0.003 inch, loose fit, replace pres-
sure pump body, gear spacer plate, and scavenger pump body. In-
spect lapped surface of pressure pump body for scratches or imbedded
chips. If surface is damaged, replace pressure pump body, gear spacer
plate, and scavenger pump body.
b. Gear Spacer Plate. Handle gear spacer plate with extreme
care to avoid damaging lapped surfaces. Inspect spacer plate shaft
bores for heavy scratches and scoring. Measure clearance between
shaft bores and shafts. If bores are severely scratched or scored, or
either clearance between shaft bores and shafts exceeds 0.0025 inch,
loose fit, replace pressure pump body, spacer plate, and scavenger
pump body.
c. Scavenger Pump Body.
( 1 ) Measure Shaft Bore Clearances. Inspect scavenger pump
body thoroughly and use extreme care in handling to prevent damage
to the lapped surface. Measure shaft bore clearances. If clearance
between scavenger pump body bore and pressure pump driven shaft
exceeds 0.0025 inch, loose fit, or clearance between scavenger pump
body bore and pressure pump drive shaft exceeds 0.0035 inch, re-
place pressure pump body, spacer plate, and scavenger pump body.
(2) Inspect Relief Valve Seat. Inspect relief valve seat for
rough edges. If seat has a rough edge, replace valve seat. To re-
place the valve seat, tap through the seat with a standard 3 /s-inch,
16-thread tap. Place several washers under the head of a 3 /s-inch,
socket-head set screw, and with a socket-head set screw wrench, turn
■screw into seat. When the washers shoulder against the relief valve
bore, turn the wrench sharply until the seat is drawn from the pump
body. The seat is installed with a press fit, and the wrench must be
turned heavily to withdraw the seat. Discard the seat and install
a new one. To install new relief valve seat, insert plunger in dummy
relief valve body. Place new seat on end of plunger. Screw dummy
body into seat opening in scavenger pump body. Screw dummy
body in until it is flush against scavenger pump body spot facing. In-
sert %-inch rod through opening in dummy body. Strike rod sharply
174
TM 9-1725
51
DISASSEMBLY, CLEANING, INSPECTION, REPAIR, AND
ASSEMBLY OF SUBASSEMBLIES
to drive seat into position. Remove rod. Unscrew dummy body,
and remove plunger from dummy body.
d. Relief Valve. Place relief valve ball between four prongs in
valve body. Measure clearance between ball and prongs with feeler
gage. If the clearance is greater than 0.014 inch, replace valve body.
Inspect ball for nicks, cracks, or flat spots. Replace ball if it is
damaged. Check the plunger to see if it slides into the relief valve
spring so that when the spring is compressed, there is no evidence of
binding. Test spring compression. Spring should have a tension
between 4.95 and 6.05 pounds at a spring length of 1.25 inches. If
tension is less than 4 pounds, replace spring. Inspect condition of
threads on the relief valve nut, and the condition of the bore which
accommodates the spring. If threads are worn or damaged, or if bore
is rough, smooth bore with fine stone, and replace nut.
e. Inlet Screen Assembly. Inspect screen for damage. Replace
screen if punctured or otherwise damaged. Check inlet strainer
spring for compression. With the spring measuring 3.125 inches in
length, spring tension should be 6 pounds. If tension is less than 5
pounds, replace spring. Inspect condition of threads on thermometer
» adapter. Check hole in adapter to see that it is smooth. Replace
adapter if threads are damaged or if bore is rough.
f. Gears.
(1) Oil Pump Drive Gear. Check gear for condition of teeth.
If teeth are even slightly worn, grooved, chipped, or broken, replace
gear. Install gear in pressure pump body, and measure running clear-
ance with feeler gage. If clearance is not within limits prescribed
(Table of Limits), replace gear. Measure clearance between gear
shaft and bore opening in pressure pump body. If gear shaft is less
than minimum limits prescribed (Table of Limits), replace gear. If
bore is larger than maximum limits prescribed by Table of Limits,
replace pressure pump body, gear spacer plate, and scavenger pump
body. Inspect under side of gear and top of pressure pump body
to determine if the top of the pressure pump body provides adequate
thrust for the gear. Polished surfaces -on both the gear and pressure
pump body indicate adequate thrust.
(2) Pressure Pump Gears. Check condition of gear teeth,
and replace gear and shaft assembly if teeth are even slightly chipped,
worn, grooved, or cracked. Check end clearance and running clear-
ance of both the drive and driven gears in relation to the pressure
pump body and the gear spacer plate. If the end, or running, clear-
ances of either gear is more than 0.005 inch, loose fit, replace gear
and shaft assembly. Operate gears with master gear and check for
backlash. If the gears have more than 0.008-inch backlash, replace
gear and shaft assemblies. Excessive backlash affects the priming
175
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ORDNANCE MAINTENANCE - ORDNANCE ENGINE
MODEL R975-C4 (CONTINENTAL)
qualities of the pump and backlash must be held to the prescribed
minimum. Check condition of drive shaft splines, and replace gear
and shaft assemblies if splines are damaged.
(3) Scavenger Pump Gears. Inspect both scavenger pump drive
and driven gears for condition of gear teeth. Measure end play and
running clearances, and check backlash. If end play exceeds, 0.005
inch, loose fit, if backlash exceeds 0.007 inch, or if the gears are even
slightly damaged, replace gears.
(4) Govenor Drive Gears.
(a) Governor Drive Gear Bushing. Install governor drive gear,
and measure clearance between the drive gear shaft and shaft bush-
ing in scavenger pump body. Clearance should measure between
0.001 and 0.0025 inch, tight fit. If bushing is worn beyond maximum
inside diameter prescribed, replace bushing. To replace bushing,
drill out locking pin, and drill out bushing until thin shell remains.
Break out remaining shell. Clean up bearing bore. Press new bush-
ing into bore, and broach to proper inside diameter. Drill hole
through scavenger pump body guide hole and bushing. Install lock-
ing pin through hole and bushing.
(b) Governor Drive Gear. Inspect gear teeth, and replace gear if
teeth are worn or damaged.
( c ) Governor Drive Intermediate Gear. Inspect condition of gear
teeth, and replace gear if teeth are damaged. Check condition of gear 1
spline, and slip gear over pressure pump drive shaft spline. Measure
spline clearance. If splines are loose fitting, replace intermediate gear.
g. Body Screws. Inspect four pressure pump body screws to
make sure they are straight, and that the threads are square and in
good condition. If screws are bent, or threads are not square, screws
will tend to cock pressure pump body when the body is assembled
to the gear spacer plate. Replace bent screws or screws with dam-
aged threads.
li. Scavenger Pump Body Cover. Inspect cover to make sure
that it is not warped, cracked, or dented. Replace cover if it is
warped or damaged.
52. ASSEMBLY.
a. Install Pressure Pump Drive Shafts. Lubricate two pressure
pump drive shafts and gears. Make sure that lapped surface of gear
spacer plate is free from chips and dirt. Install shafts in gear spacer
plate holes. Make sure that the lower edges of gear teeth are up
against countersink in the spacer plate holes. Install two Woodruff
keys in keyway in pressure pump driven shaft below spacer plate.
b. Install Scavenger Gears. Lubricate the scavenger pump
gears. Slide scavenger pump drive gear over the pressure pump
176
TM 9-1725
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DISASSEMBLY, CLEANING, INSPECTION, REPAIR, AND
ASSEMBLY OF SUBASSEMBLIES
driven shaft, carefully. Make sure to line up the gear keyway with
the Woodruff keys. Slide gear on by hand and into position.
CAUTION: Do not drive it onto shaft. Press the pressure pump
body driven gear, and the scavenger pump drive gear against the
gear spacer plate by hand. Slide the scavenger pump driven gear
over the pressure pump drive shaft, and mesh with scavenger pump
drive gear.
c. Install Governor Drive Gear. Lubricate governor drive gear.
Install gear in scavenger pump body so that end of gear shaft fits
through and rests in bushing in governor mounting pad.
d. Install Pressure Pump Body and Spacer Plate Assembly.
Make sure that there are no chips or dirt, on lapped matching sur-
faces of the gear spacer plate and scavenger body. Lubricate lower
ends of pressure pump drive shafts, and put a small amount of lubri-
cant on scavenger gears. Do not put an excessive amount of lubri-
cant on the driven shaft. Clearances in the scavenger body are so
close that excess oil in the shaft bore will create a hydraulic lock,
which will prevent the shaft from going to the bottom of the shaft
bore. Install the governor intermediate drive gear in position inside
scavenger body, and mesh it with governor drive gear. Holding gear
spacer plate and shaft assembly upright, lower the assembly into the
scavenger body, being careful not to force the pilot pins from their
true position. Splines on the lower end of the pressure pump drive
shaft will mesh with the splines in the governor drive intermediate
gear, holding that gear in position.
e. Install Pressure Pump Body. Hold the pump already assem-
bled in upright position so that assembly does not become separated.
Lubricate top of pressure pump drive s' Its. Put small amount of
lubricant on gear teeth. Install pressure pump body over shafts and
gears, and onto pilots extending from gear spacer plate. Insert four
pressure pump body holding screws through pressure pump body.
Tighten screws slightly more than fingertight. Insert pressure pump
drive gear in top of pressure pump body to spline with drive shaft.
Operate oil pump drive gear to test free operation of all gears and
shafts. If gears and shafts operate freely, tighten four holding screws
uniformly. Keep testing free operation of gears as screws are being
tightened. Any binding noticed during the screw-tightening proced-
ure, may be due to misalinement of the pressure pump body, im-
proper gear end clearance, or slight misalinement of the dowel pins.
Lightly tap pressure pump body laterally in various directions with a
rawhide, or plastic, hammer. Operate gears with oil pump drive gear
to determine if tight spots exist on any side of pump. Any impossi-
bility to operate gears freely indicates improper assembly or defective
parts. Disassemble the pump, reinspect the parts, and replace any de-
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TM 9-1725
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ORDNANCE MAINTENANCE - ORDNANCE ENGINE
MODEL R975-C4 (CONTINENTAL)
fective parts. If the gears operate freely, tighten the four pressure
body holding screws securely, and secure with lock wire. Lock wire
the two front screws together, and the two rear ones together.
f. Install Relief Valve Assembly. Place new gasket over relief
valve body, and screw valve body into scavenger pump body. Insert
valve ball into valve body. Place plunger in valve spring, and push
spring and plunger through valve body to valve ball. Install relief
valve adjusting screw, and turn screw into valve body about half way
(half the number of threads). Place new washer on adjusting screw.
Install lock nut. Leave off second washer and relief valve cap until
oil pump has been adjusted properly.
g. Install Strainer Assembly. Insert inlet strainer into scaven-
ger body. Place spring in strainer. Place new gasket in thermometer
adapter, and screw adapter into scavenger body.
h. Install Scavenger Body Cover. Install scavenger body cover
gasket over studs around cover opening on scavenger body. Place
cover over studs. Place washers and stud nuts on studs. Tighten
nuts. Install and tighten palnuts.
53. TESTS AND ADJUSTMENTS.
a. Install Oil Pump on Test Stand. Install oil pump on test
stand designed to simulate actual operating conditions when engine is
installed in vehicle. The stand should be constructed so that test
motor will drive pump at speeds ranging from 100 to 2,700 revolu-
tions per minute. The stand should be equipped to measure oil flow
and oil pressure from zero to the pump maximum values.
b. Test Pump Operation. Start test motor at any prearranged
speed. Check to see that pump is priming at 600 revolutions per min-
ute; if not, raise the speed until it does prime. With screwdriver, ad-
just relief valve adjusting screw so that at an engine speed of 800
revolutions per minute, and with the oil flow controlled between 12
and 15 gallons per minute, oil pressure registers 35 pounds. Increase
the speed of the engine. At 2,400 revolutions per minute, adjust oil
pressure to 75 pounds. If oil pressure can be adjusted to above speci-
fications, pump is operating satisfactorily. Shut off motor and remove
pump. Place pump on bench until ready to install on rear crank-
case section.
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TM 9-1725
54
DISASSEMBLY, CLEANING, INSPECTION, REPAIR, AND
ASSEMBLY OF SUBASSEMBLIES
RA PD 314827
Figure 185 — Starter Gear and Shaft — Disassembled
Section XII
REAR CRANKCASE SECTION SUBASSEMBLIES
Paragraph
Starter gear and shaft 54
Generator idler gear and shaft 55
Generator drive gear support 56
Accessory drive shaft assemblies 57
Three-way accessory drive housing 58
Tachometer and three-way accessory drive 59
Tachometer drive assembly 60
Fuel pump and mounting 61
Accessories 62
54. STARTER GEAR AND SHAFT.
a. Disassembly. Remove starter shaft bolt spring by pushing
starter shaft bolt spring retainer down to uncover pin installed through
bolt. Remove pin from bolt. Pull retainer, spring and spring seat
from bolt, and remove bolt.
b. Cleaning, Inspection, and Repair. Clean all parts in dry-
cleaning solvent, and coat with light film of lubricating oil. Care-
fully inspect matching serrations on the pinion gear and drive shaft
gear. Check gears for condition, freedom from mars or scratches,
and for fit. If any of these three machined parts are unserviceable,
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ORDNANCE MAINTENANCE - ORDNANCE ENGINE
MODEL R975-C4 (CONTINENTAL)
Figure 1 86 — Generator Drive Gear Support — Disassembled
replace all three with a new matched set. Inspect spring for tension,
which should be from 6 to 8 pounds when spring is compressed to
1.375 inches. Inspect bolt, spring seat, retainer, and pin. Replace
any unserviceable parts.
c. Assembly. Reassemble bolt and starter drive shaft gear by
reversing disassembly procedure (subpar. a, above). Make sure to
install retainer with flanges up so that flanges will retain the bolt pin
in position. Do not assemble starter gear to starter drive shaft gear.
55. GENERATOR IDLER GEAR AND SHAFT.
a. Disassembly. The generator idler gear and generator idler
gear shaft assembly is an integral unit.
b. Cleaning, Inspection, and Repair. Clean gear and shaft with
dry-cleaning solvent, and coat with light film of lubricating oil. In-
spect shaft for scores, pits, scratches, and evidence of wear. Measure
diameter of shaft with micrometer. Diameter should measure be-
tween 0.8725 and 0.8735 inch. If diameter is worn beyond allowable
limits (Table of Limits), replace assembly. Inspect face of flange
at end of shaft for burs or roughness. Remove burs or roughness
with fine stone, and polish with crocus cloth. Inspect generator idler
gear teeth for cracks, or excessive wear. Replace assembly if either
of these conditions is found. Inspect gear bushing for roughness,
scores, or erosion.
c. Assembly. Place assembly on bench until ready to instalL
180
TM 9-1725
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DISASSEMBLY, CLEANING, INSPECTION, REPAIR, AND
ASSEMBLY OF SUBASSEMBLIES
56. GENERATOR DRIVE GEAR SUPPORT (fig. 186).
a. Disassembly. Remove nut and washer from generator inter-
mediate gear support stud. Remove intermediate gear from support.
Remove lock ring and nut from generator drive gear shaft. Remove
generator drive gear from support.
b. Cleaning, Inspection, and Repair. Have gears given a mag-
naflux inspection. Replace cracked gears. Inspect gears for condi-
tion of teeth and journals. Smooth up any slight imperfections with
fine stone. Replace worn or damaged gears. Inspect gear support for
cracks and general condition. Replace support if it is damaged. In-
spect condition of intermediate gear stud. Blow out all oilholes.
Drill out pin. Unscrew, and replace pin if threads are worn or dam-
aged. Inspect condition of gear bushings. If bushings are in good
condition, check diameters with inside micrometer or plug gage. If
drive gear bushing is damaged or is worn beyond allowable limits,
replace support. The bushing should measure between 0.6245 and
0.6255 inch. If intermediate gear bushing is damaged, or worn
beyond allowable limits, replace support.
c. Assembly, Oil all parts, and reassemble support and . gears by
reversing disassembly procedure (subpar. a above). Place assembly
on bench and protect it from dirt and dust.
57. ACCESSORY DRIVE SHAFT ASSEMBLIES.
a. Disassembly. Assemblies have already been removed, and are
not further disassembled.
b. Cleaning, Inspection^ and Repair. Clean parts in dry-clean-
ing solvent, and coat with light film of engine oil. Have assemblies
given magnaflux inspection. Inspect accessory drive shafts for gall-
ing, scoring, and wear at bearing locations. Inspect condition of
threads on ends of shafts. Check teeth on integral gear shaft for
scores and wear. Examine magneto couplings for wear. Check
magneto coupling splines for scores and wear. Inspect magneto drive
splines for fit within magneto couplings and for condition of splines.
Remove scores from gear teeth and bearing journals with fine stone,
and polish with crocus cloth. If threads at end of shaft are damaged,
or either shaft is cracked, replace assembly. If any other part per-
taining to shaft is damaged or badly worn, replace the assembly.
Blow out oilhole running through each shaft with compressed air.
c. Assembly. No assembly is made until shafts are installed in
crankcase. Place assemblies on bench and cover them to protect
them from dirt and dust.
58. THREE-WAY ACCESSORY DRIVE HOUSING.
a. Disassembly. Cut safety wire from palnuts, and remove palnuts
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ORDNANCE MAINTENANCE - ORDNANCE ENGINE
MODEL R975-C4 (CONTINENTAL)
RA PD 314828
Figure 187 — Three-way Drive Housing Assembly — Disassembled
and washers. Remove, in order, vacuum pump substitute cover, gas-
ket, left-hand vacuum pump adapter, gasket, and vacuum and fuel
pump drive shaft.
b. Cleaning, Inspection, and Repair. Clean all parts in dry-
cleaning solvent, and coat with light film of engine oil. Inspect
vacuum and fuel pump drive gear, and shaft, for condition of teeth
and splines. Inspect journals for scores, scratches, or any indications
of wear. Inspect housing, adapter, and cover for cracks and general
condition. Inspect studs in housing for tightness and condition of
threads. Inspect housing, left-hand fuel pump gear bushing, and
fuel pump adapter gear bushing for finish and for excessive wear.
Check diameter of bushings with micrometer or plug gage.* If diame-
eter of adapter or housing bushings are greater than allowable limits
(Table of Limits), or if bushings are damaged, replace adapter or
housing. Replace any other unserviceable parts.
c. Assembly. Oil parts of assembly; reinstall new gaskets; and
reassemble assembly, reversing disassembly procedure (subpar. a,
above).
59. TACHOMETER AND THREE-WAY ACCESSORY DRIVE.
a. Disassembly. Remove cotter pin, nut, and three-way drive
gear from inner end of adapter. Remove cover, gasket, and shaft
from outer end.
*The drive gear housing should measure between 0.937 and 0.938 inch; the
left-hand fuel pump bushing between 0.8775 and 0.8785 inch; and the fuel pump
adapter drive gear bushing between 0.7510 and 0.7520 inch.
182
TM 9-1725
59
DISASSEMBLY, CLEANING, INSPECTION, REPAIR, AND
ASSEMBLY OF SUBASSEMBLIES
KEY / — TACHOMETER AND
THREE-WAY DRIVE GEAR
ADAPTER, DRIVE GEAR
SHAFT
THREE-WAY DRIVE GEAR
SHAFT
GASKET-
COVER-
RA PD 314841
Figure 188 — Tachometer and Three-way Accessory Drive
— Disassembled
-GASKET
-RETAINER
- HOUSING
DRIVE SHAFT GEAR
SPACER
BEARING
TACHOMETER
DRIVE SHAFT
SCREW -
RA PD 314829
Figure 189 — Tachometer Drive Assembly — Disassembled
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ORDNANCE MAINTENANCE - ORDNANCE ENGINE
MODEL R975-C4 (CONTINENTAL)
ADAPTER ELBOW
ECCENTRIC
GASKET
BUSHING
FUEL PUMP DRIVE SHAFT
FUEL PUMP ASSEMBLY -
WASHER -
NUT-
RA PD 314830
SCREW
Figure 190 — Fuel Pump Adapter Elbow — Disassembled
b. Cleaning, Inspection, and Repair. Give gears magnaflux in-
spection. Inspect gears for condition of teeth, splines, threads, and
journal surfaces. Inspect adapter and cover for cracks, and condition.
Inspect tachometer and three-way accessory drive cover bushings for
roughness and indications of wear. Check diameter of bushings with'
micrometer or plug gage. Bushing diameters should measure between
0.7495 and 0.7505 inch. If diameter of either bushing is greater than
allowable limits, replace cover or adapter. Replace any parts that
are worn or otherwise unserviceable.
c. Assembly. Oil all parts, and reassemble tachometer and three-
way accessory drive, reversing the disassembly procedure (subpar. a,
above). Be sure to use a new gasket under cover.
60. TACHOMETER DRIVE ASSEMBLY.
a. Disassembly. Remove protective caps from outer ends of
bronze bushings. Remove lock wire, six cap screws, and washers
which retain cover on tachometer housing (fig. 189). Remove cover
and gasket. Unscrew both tachometer driven shaft bronze bushings
from housing. Withdraw two sleeves and gaskets. Pry out tachom-
eter drive shaft ball bearing retainer located at inner end of housing.
Remove cotter pin and nut holding drive shaft gear and spacer in
place. Remove gear, spacer, and gear key. Pull out tachometer
drive shaft, drive shaft gear, and inner ball bearing, as a unit. Remove
other ball bearing from housing.
b. Cleaning, Inspection, and Repair. Clean all parts in dry-
cleaning solvent, and oil with light film of engine oil. Inspect bush-
ings for condition of threads and for condition of inner machined sur-
faces. Replace badly scored or worn bushings. Give gears magnaflux
inspection for cracks. Inspect gears for condition of teeth and jour-
nals. Inspect teeth, journal, and threads on drive shaft. Inspect
184
TM 9-1725
60
DISASSEMBLY, CLEANING, INSPECTION, REPAIR, AND
ASSEMBLY OF SUBASSEMBLIES
X RA PD 314856
Figure 191 — Phantom View Fuel Pump Adapter Elbow
teeth and key way on drive shaft gear. Turn bearings slowly to check
for flat spots, scores, pits, or excessive wear. Inspect housing and
cover for cracks and general condition. Replace any unserviceable
parts.
c. Assembly. The tachometer drive gear and shaft assemblies
incorporate sleeves in which spiral oil grooves are milled. During
normal operation and when properly assembled, the tachometer driven
gears rotate in opposite directions to each other. The spiral oil
grooves are milled in such a direction, that during rotation, the oil is
forced into the interior of the tachometer drive gear housing. Inter-
changing the driven gears reverses the direction of the spiral oil
grooves and tends to force the oil out of the tachometer drive gear
shaft housing which results in oil leakage. To check before assembly,
select one of the driven gears and rotate it in a counterclockwise
direction while facing the gear end. The spiral oil groove milled in
the shaft of the driven gear assembly that should be located in the
upper position, will run in toward the gear end of the assembly. If
not, select the remaining driven gear, and repeat the check. See that
ball bearing, spacer, tachometer drive gear nut, and cotter pin are
properly installed on the driving end of the tachometer drive shaft.
Install retainer. Assemble the drive shaft in the tachometer drive
housing. Assemble the tachometer driven shafts, bushings, and gas-
185
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ORDNANCE MAINTENANCE - ORDNANCE ENGINE
MODEL R975-C4 (CONTINENTAL)
kets in the tachometer drive housing. Tighten the bushings and make
sure that driven shafts have the proper end clearance. Pack housing
with petrolatum, and install the other drive shaft ball bearing. Place
housing cover and gasket in position. Insert cover attaching screws,
tighten screws, and secure with lock wire.
61. FUEL PUMP AND MOUNTING.
a. Disassembly. Remove cotter pins from two nuts. Remove
nuts and washers, and remove fuel pump from adapter elbow. Take
out three screws, and remove bushing from elbow. Lift fuel pump
drive shaft and eccentric out of elbow.
b. Cleaning, Inspection, and Repair. Clean all parts in dry-
cleaning solvent, and coat with light film of oil. Inspect adapter elbow
for cracks and general condition. Inspect drive shaft for condition,
paying particular attention to eccentric and journals. Inspect bushing
for condition of external surfaces and for wear on inner diameter.
Check diameter with micrometer or plug gage, and replace bushing,
if it is out of round or the diameter is greater than allowable limits
(Table of Limits). Replace any other unserviceable parts. If fuel
pump requires service attention, refer to procedures given in TM 9-
1828A.
c. Assembly. Reinstall bushing, fuel pump, and drive shaft, on
adapter elbow. Be sure fuel pump is installed so that the control
arm is on top of the drive cam in the adapter elbow. Put assembly
aside until ready to install in rear crankcase.
62. ACCESSORIES.
a. For disassembly, cleaning, inspection, repair, and assembly of
carburetor, fuel pump, booster coil, governor, magnetos, generator,
starter, and primer, refer to pertinent technical manuals. Carburetor
is covered in TM 9-1826B; fuel pump, TM 9-1828A; Auto-Lite
booster coil, TM 9-1825B; Delco-Remy booster coil, TM 9-1825A;
governor, TM 9-1750D; magnetos, TM 9-1750C; generator, TM 9-
I750D; starter, TM 9-1825A; and primer, TM 9-1750D. For make
and models of these accessories, refer to tabulated data (par. 4).
Section XIII
IGNITION HARNESS
Paragraph
Disassembly 63
Inspection, cleaning, and repair 64
Assembly 65
186
TM 9-1725
63
DISASSEMBLY, CLEANING, INSPECTION, REPAIR, AND
ASSEMBLY OF SUBASSEMBLIES
SPARK PLUG OUTLET LUG-
METAL GASKET — i
R-9
- MAGNETO CONDUIT
OUTLET LUG
FERRULE -
(CIGARETTE CONNECTOR-
MANIFOLD
RING
/ / V\— MAGNETO
VV
/ / (’5^1 CONDUITS if
i if /n
/ ADAPTER 111
\ ELBOW gj
\ V- MOUNTING CLIP
/ &
F-4 R-4
F-5
-SPARK PLUG
IGNITION
CABLE CONDUIT
IGNITION SHIELDING HARNESS REWIRING CHART
Rear Spark Plugs — Left Magneto Front Spark Plugs — Right Magneto
RA PD 314837
Figure 192 ~ Ignition Shielding Harness
187
TM 9-1725
63-64
ORDNANCE MAINTENANCE - ORDNANCE ENGINE
MODEL R975-C4 (CONTINENTAL)
63. DISASSEMBLY (fig. 192).
a. At each major engine overhaul, replacement of all the wiring
in the ignition harness is recommended.
b. Remove Cable from Distributor Blocks. Remove all piercing
screws from each distributor block, and withdraw the ignition cables
from the distributor block.
c. Remove Magneto Elbows from Ignition Cables. Unscrew the
knurled nut securing the magneto adapter elbows to the magneto
conduits, and slide the adapter elbows off the ignition cables.
d. Remove Magneto Conduits. Unscrew the knurled nut secur-
ing each magneto conduit to the ignition harness, and slide the mag-
neto conduit off the ignition cables.
e. Remove Cigarette Connector Protectors. Unscrew cigarette
connector protector from each spark plug wire conduit elbow and re-
move protector.
f. Separate Cigarette Connectors. Straighten the strands of each
spark plug cable bent over the sides of the hollow rivet in each
cigarette connector, and remove connector from each cable.
g. Remove Spark Plug Terminal Elbows. Unscrew coupling nut
securing each elbow to spark plug conduit, and remove elbows.
h. Remove Spark Plug Conduits. Unscrew the coupling nut at-
taching spark plug conduit to the manifold ring. Slide the conduit
and rubber covering off the cable. Repeat this procedure for each
spark plug cable.
i. Disconnect Manifold Ring. Unscrew the knurled nut holding
the two halves of the manifold ring. Disconnect ring halves. With-
draw ignition cables from the magneto outlet lug in one section of
ring in reverse of the wiring order (fig. 192). Withdraw cables from
other half of ring in reverse of the wiring order.
64. INSPECTION, CLEANING, AND REPAIR.
a. Inspection, Examine the inside surfaces of all parts, par-
ticularly at the connections for nicks, burs, and abrasions which may
tear or otherwise damage the cable insulation during the wiring of
the harness. Inspect the two halves of the manifold ring for cracks
and punctures. Inspect the conduits for abrasions or breaks in the
braiding wire, and replace if necessary. Examine the threads of all
outlets and coupling nuts. Examine all cigarette connectors. If they
are burned, or if the spring is broken, replace them.
b. Cleaning. Clean dirty conduits with dry-cleaning solvent. With
a wire brush, clean the threads of aluminum couplings to remove
oxidation which sometimes forms on the threads. This oxidation
breaks the grounded circuit and causes radio interference.
188
TM 9-1725
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DISASSEMBLY, CLEANING, INSPECTION, REPAIR, AND
ASSEMBLY OF SUBASSEMBLIES
c. Repair. Silver solder, or braze, all cracks in the manifold
ring. Silver solder to the manifold ring any loose mounting clips.
Dress up damaged threads. Replace defective conduits. Replace
defective outlet lugs. To do this, use a torch having a wide flame (or
two torches if necessary) to heat the circumference of the joint uni-
formly and lift off the outlet lug. Silver solder a new outlet lug to
the manifold ring. If necessary, half of the manifold ring may be
replaced instead of several outlet lugs. In case of a wire shortage,
it may be advisable to replace one or more ignition cables. To re-
place a single ignition cable, remove the spark plug terminal elbow
and spark plug conduit, and withdraw the cable from the distributor
block. To the spark plug end of the cable, solder a 6-foot length of
No. 14 wire. Withdraw the cable from the magneto outlet lug, and
unsolder the defective cable from the stringer wire which is now in
the manifold ring in place of the cable. Cut a length of cable, equal
in length to the one removed, and solder it to the stringer wire at the
magneto end. Apply powdered talcum to the cable, and pull the
cable through the manifold ring by the stringer wire.
65. ASSEMBLY.
a. Cut Ignition Cables. During reassembly after overhaul, re-
place all ignition cables. Cut ignition cables to the required lengths
(fig. 192). To facilitate the wiring of the manifold ring, apply
powdered talcum or mica to each cable before feeding it through the
manifold ring.
b. Install Ignition Cables. Start feeding the cables through the
spark plug outlet lugs, and follow the wiring order (fig. 192). To
aid in pulling the cable from the magneto outlet lug, use a piece of
wire with the end formed into a hook. Insert one finger into the mag-
neto outlet lug, and feed the cable through the ring until it is felt at
the magneto outlet lug. Pull the cable out with the hook. If it be-
comes difficult to install the last few cables, start feeding at the mag-
neto outlet lug. As each cable is installed in the manifold ring, mark
it on the magneto end for identification so that it will be installed
correctly in the distributor block.
c. Install and Connect Conduits. Slide the proper conduit over
the cable at the spark plug end, and secure the conduit to the mani-
fold ring with the coupling nut. Cut each cable to a length of 3%
inches measured from the end of the conduit. Slide the elbow over
the cable, and secure it to the conduit with the coupling nut.
d. Install Cigarette Connectors. Strip about % inch of the in-
sulation from end of cable. Slide the cigarette connector over the
cable. Thread the stripped end of the cable through the hollow rivet
of the cigarette connector. Separate the strands, and bend them over
189
TM 9-1725
65-67
ORDNANCE MAINTENANCE - ORDNANCE ENGINE
MODEL R975-C4 (CONTINENTAL)
the sides of the hollow rivet. Install a protector over each cigarette
connector.
e. Install Magneto Conduits. Slide the magneto conduits over
the cables, and secure the conduit to the manifold ring by the knurled
nut.
f. Attach Cables to Distributor Blocks. Thread the cables for
each magneto adapter elbow through the elbow, and attach the elbows
to the conduits by the knurled nuts. Remove about V 2 inch of the
insulation of each wire. Separate the strands, space them evenly,
and fold them back over the insulation. Install the proper ferrule,
stamped with the number denoting its installation position in the dis-
tributor block. Swage the ferrule in place. Insert the cables in the
distributor block so that the ferrule number corresponds with the
number on the distributor block. Secure the cables in the distributor
block with the piercing screws. If the extending ends of the cables
are too long, feed them back into the manifold so that the extra length
will be available for future repairs.
g. Test Harness. Test the harness with a high tension testing set
following instructions furnished with the testing set If a high tension
testing set is not available, use a simple bell and battery set, and test
each wire.
Section XIV
FLYWHEEL AND FAN
Paragraph
Disassembly 66
Cleaning 67
Inspection and repair 68
Assembly 69
66. DISASSEMBLY.
a. Remove Fan from Flywheel. Mark fan and flywheel with
prick punch for identification when reassembling. Drive out 12 fly-
wheel ring bolts from flywheel and fan. Lift off fan (fig. 193).
b. Remove Separator Pin Springs. Cut and remove lock wire.
Remove two cap screws and spacers from each separator pin spring
on flywheel.
c. Remove Separator Pins. Remove separator pins from holes
in flywheel (fig. 250).
67. CLEANING.
a. Clean all dirt and grease from flywheel and fan, with dry-clean-
ing solvent. Clean mating surfaces of flywheel and fan.
190
TM 9-1725
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DISASSEMBLY, CLEANING, INSPECTION, REPAIR, AND
ASSEMBLY OF SUBASSEMBLIES
*- GUIDE BOLTS -v
FAN J L FLYWHEEL RA PD 53592
Figure 1 93 — Assembling Fan and Flywheel
68. INSPECTION AND REPAIR.
a. Inspect Flywheel. Inspect carefully fot cracks in both flywheel
and hub. Inspect for loose rivets. Inspect splines inside hub, to be
sure splines are free from nicks and scores. Inspect surface of fly-
wheel which contacts clutch facing, to be sure this surface is free from
any rough spots or irregularities which will not permit good contact
with facing. Inspect tapered cone seats, at each end of hub, for rough
or flat spots, which would indicate that flywheel has been loose on
shaft. Clean up separator pin holes.
b. Inspect Fan. Inspect fan blades and hub carefully for cracks
or any indication of interference. Replace fan if any cracks are noted.
c. Inspect Separator Springs. Inspect separator springs to see
that they are not cracked or broken. Replace damaged springs. Dis-
card spacers and cap screws.
d. Inspect Separator Pins. Clean up separator pins. Make sure
pins are free to travel back and forth in holes in flywheel by pushing
on them. Replace worn or damaged pins.
69. ASSEMBLY.
a. Install Separator Springs on Flywheel. Using new cap screws
and spacers, reinstall separator springs on flywheel. Use two cap
screws to install each spring. Tighten screws and fasten them with
lock wire (fig. 193).
191
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ORDNANCE MAINTENANCE - ORDNANCE ENGINE
MODEL R975-C4 (CONTINENTAL)
b. Assemble Fan to Flywheel. Place three guide bolts in fan
(fig. 193). Lift fan, and position it over flywheel with index marks
lined up. Guide bolts over matching bolt holes in flywheel. Drive
bolts all the way through assembly.
Section XV
MISCELLANEOUS SUBASSEMBLIES
Paragraph
Cowling 70
Air deflectors 71
Engine supports 72
Exhaust manifold collector ring 73
Sump assembly 74
70. COWLING (fig. 241).
a. Cleaning, Inspection, and Repair. Clean cowling assembly,
and inspect it for dents and evidences of chafing. See that sections are
fastened together securely and secured to the ring. Examine Dzus
fasteners for looseness or signs of mutilation. Replace loose or muti-
lated fasteners. If cowling is dented, hammer it into its original
shape. Weld all cracks unless location of cracks makes this inad-
visable. Replace cracked parts which cannot be welded. When re-
placing riveted part, drill out old rivets. Install new part, and drive
new rivets. Do not hammer rivets out
71. AIR DEFLECTORS (fig. 194).
a. Cleaning, Inspection, and Repair. Inspect air deflectors for
bends, cracks, tightness of rivet, and condition of retaining holes and
Dzus fasteners. Replace loose rivets, and loose or mutilated fasteners.
Replace or weld all cracked parts. Hammer out bent parts.
72. ENGINE SUPPORTS.
a. Cleaning, Inspection, and Repair. Clean and inspect engine
rear support for cracks, weld breaks, bends, or other evidence of
distortion (fig. 34). Replace damaged, or distorted support. Inspect
engine front support carefully for cracks, burs, nicks, scratches, or
sharp corners (fig. 36). Remove burs or nicks with fine stone. Re-
place defective support.
73. EXHAUST MANIFOLD COLLECTOR RING (fig. 245).
a. Cleaning, Inspection, and Repai.’. Clean and make thorough
inspection of exhaust manifold assembly. Look for cracks, bends,
dents, or erosion. Inspect mounting flanges for cracks, warping, or
192
TM 9-1725
73-74
DISASSEMBLY, CLEANING, INSPECTION, REPAIR, AND
ASSEMBLY OF SUBASSEMBLIES
Figure 194 — Inter-cylinder and Cylinder Head Air Deflectors
other defective conditions. Replace damaged individual sections of
assembly. Replace sections by loosening clamp cap screws holding
ring sections together and removing section. Remove clamps. In-
stall new clamps. Position new section in place, and tighten clamp
cap screws.
74. SlIMP ASSEMBLY (fig. 242).
a. Cleaning, Inspection, and Repair. Clean sump tanks and
tubes. Inspect tanks for leaks, under pressure, if possible. Check
for cracks and dents. Replace tanks if they are damaged or if they
leak. Inspect spider tubes for leaks, dents, and condition of welded
seams. Replace damaged spider. Check general condition of front
drain tube, welds, and machined surface. Replace damaged tube.
Inspect strainer housing for leaks and general condition, and replace
if damaged. Check strainer screen for general and thread condition
of plug end. Inspect conditions of threads on spider plug. If threads
are worn, install new strainer or spider plug. Check spring on front
drain tube. Install new seal. Replace all hose and hose clamps.
193
TM 9-1725
75
ORDNANCE MAINTENANCE - ORDNANCE ENGINE
MODEL R975-C4 (CONTINENTAL)
CHAPTER 5
ASSEMBLY OF SUBASSEMBLIES
Paragraph
Diffuser and rear crankcase sections, assembly and installation 75
Main and front crankcase sections, assembly and installation . 76
Cylinder, valve, and valve operating mechanism installation . 77
Accessories and miscellaneous subassemblies, installation .... 78
Flywheel, fan, and clutch installation 79
75. DIFFUSER AND REAR CRANKCASE SECTIONS, ASSEM-
BLY AND INSTALLATION.
a. Install Rear Crankcase Section on Stand. Remove rear
crankcase section from inspection bench, and attach to assembly
stand.
b. Install Starter Shaft Seal. Make sure that fuel distribution
chamber is absolutely clean, and free from burs and scratches. In-
stall new rubber seal complete with supporting bushing (fig. 196).
Place new seal on starter seal support, and insert support in starter
shaft opening. Using an old starter shaft bushing as a driver, drive
assembly into opening until it bottoms on starter shaft bushing
(fig. 196).
c. Install Generator Idler Gear and Shaft. Place gasket over
generator idler gear shaft flange studs. Insert gear through slotted
starter opening (fig. 178). Position gear with long end of bushing
journal up, directly under shaft hole opening. Tap shaft into posi-
tion. Use a soft hammer, if necessary. Install plug in center of idler
gear shaft flange. Install two washers and attaching nuts over studs.
With lock wire, fasten the nuts to two nearby plugs.
d. Install Generator Drive Gear Support. Install gasket over
generator mounting studs, with dowel hole in gasket over dowel.
Position generator drive gear assembly on studs. Line up hole in sup-
port over dowel. If necessary, rotate generator idler gear through
starter opening to mesh idler gear with the generator drive gear. Push
support all the way back on studs (fig. 33). Tap support with soft
hammer to make sure it is all the way back. Install generator cover
over support, and secure it in place with two nuts tightened finger-
tight. Install cover on starter opening.
e. Install Accessory Drive Shafts and Seals. Place each acces-
sory drive shaft in bushing in rear crankcase section with magneto
coupling up. Lubricate the leather backing on the metal oil seals
thoroughly. Install spreading tool in end of accessory drive shaft
opening. Install seal on spreader. Place alining bar through retain-
194
STARTER
TM 9-1725
75
ASSEMBLY OF SUBASSEMBLIES
lllFFI ISFP AAO INTJhJfi ElAKinF
ACCESSORY SHAFT BUSHINGS
OIL HOLE FOR STAND PIPE
RA PD 314839
INDUCTION TUBE OPENINGS- 7
SUMP AND SCAVENGER PASSAGES
Figure 195 — Fuel Distribution Chamber Rear Crankcase Section
ing screw hole in seal (fig. 197). Screw bar into screw hole opening.
Push seal over the accessory drive shaft until leather backing is posi-
tioned over shaft. Remove spreading and alining tools. Using driv-
ing tool, drive seal into section until it bottoms against seat (fig. 198).
Install retaining screw. Install seal for other accessory drive shaft
in the same way. Do not double under the leather portion of seal
when they are being installed. Install small seal in end of each
magneto coupling (fig. 199).
f. Install Oil Standpipe. Moving to front of rear crankcase sec-
tion, position oil standpipe over standpipe hole located between the
two closely spaced mounting studs in mounting flange for diffuser
section. Push standpipe into hole. Be sure standpipe is pushed in
all the way and is properly seated.
g. Cover Rear Crankcase Section. Do not install additional as-
semblies on rear crankcase section until diffuser section is attached
195
AS DRIVER
l STARTER SHAFT BUSHING
1. Installing Starter Shaft Seal 2. Driving Support and Seal into Position
RA PD 314832
Figure 1 96 — Installing Starter Shaft Seal and Support
Cl I . fV- GENERATOR IDLER GEAR SHAFT FLANGE
■ DRIFT (41 -D- 1460)
CONE (41-C-2562-11)
to rear section. This permits checking the alinement of the accessory
drive gears in diffuser section bushings and matching gears in the
rear crankcase section. Install cover over front of rear crankcase sec-
tion to protect the assembly from dust and dirt.
TM 9-1725
75
ORDNANCE MAINTENANCE - ORDNANCE ENGINE
MODEL R975-C4 (CONTINENTAL)
ACCESSORY DRIVE SHAFT
Figure 197
RA PD 314780
— Alining Retaining Screw Holes for Oil Seal
196
Figure 20 J — Installing Spacers and Seals on Accessory Drive
Shaft Bushings
h. Install Spacers and Rubber Oil Seals. With rear side of dif-
fuser section facing up on bench, install spacers and rubber oil seals
over accessory drive shaft bushings (fig. 201). Press spacers and oil
seals down against diffuser ring.
198
TM 9-1725
75
ASSEMBLY OF SUBASSEMBLIES
STUDS FOR MAIN SECTION J RA PD 314824
Figure 202 — Installing Diffuser Section on Rear Crankcase Section
i. Before installing diffuser section, make sure that lock and cir-
clip are installed in rear impeller nut, that oil seals are installed, that
hold-down screws for diffuser ring have been staked, and that the
facing surfaces on the rear and diffuser crankcase sections are clean.
j. Install Diffuser Section. Coat matching flanges of rear and dif-
fuser crankcase sections with sealing compound. Spread compound
very thin. Position diffuser section on rear crankcase section studs
(fig. 202). Aline the section by noting the position of the sump drain
openings. Tap the diffuser section with soft hammer to make sure
that pilot on diffuser section enters the matching flange in the rear
crankcase section. Install two diffuser section retaining nuts on
studs. Tighten nuts to not more than 80 inch-pounds of torque.
Install cotter pins through studs and nuts, and secure the cotter pins.
k. Install Accessory Drive Gears. Install keys in keyway of ac-
199
TM 9-1725
75
ORDNANCE MAINTENANCE - ORDNANCE ENGINE
MODEL R975-C4 (CONTINENTAL)
Figure 203 — Checking End Play of Accessory Drive Gears
cessory drive gear shafts. Install gears on shafts, matching keyway in
gears with key in shaft. Do not drive gears into position. If gear and
shaft keyways line up, gears can be installed easily. Install nuts on
accessory drive gear shafts. Install fiber block between teeth of gears
to prevent gears from turning. Tighten nuts to between 425 and 450
inch-pounds of torque. Secure nuts with cotter pins. Check all gears
for end play (fig. 203). Working from the rear crankcase section,
check accessory drive shafts for slight end play and for free turning
through at least one complete revolution (fig. 204). End play should
measure not less than 0.012 inch, nor more than 0.050 inch. If drive
shafts do not turn freely, remove diffuser section, and check matching
bushing in diffuser and rear crankcase sections. When bushings are
properly alined and in serviceable condition, reinstall diffuser section
and proceed with assembly.
I. Install Starter Gear. Lubricate starter gear bushings in dif-
fuser and rear crankcase sections. Install gear and starter shaft bolt
through front of diffuser section (fig. 78). Install starter shaft
through opening in rear crankcase section (fig. 77). Mount shaft
200
TM 9-1725
75
ASSEMBLY OF SUBASSEMBLIES
OIL PUMP MOUNTING STUDS-^ RA PD 314854
Figure 2 05 — Oil Pump Mounting Studs
over starter shaft bolt, and secure bolt through shaft by installing
timing adjusting nut on end of bolt. With gears held stationary by
fiber block placed between gear teeth, tighten starter shaft bolt nut
to between 375 and 400 inch-pounds of torque. Check starter gear
201
TM 9-1725
75
ORDNANCE MAINTENANCE - ORDNANCE ENGINE
MODEL R975-C4 (CONTINENTAL)
GENERATOR IDLER GEAR GENERATOR ACCESSORY
SHAFT OPENING — . , — SUPPORT PAD , — DPIVF OF A D
MOUNTING PAD RA PD 314849
Figure 2 06 — Tachometer Drive Installed and Opening for
Three-way Housing Drive
for perceptible end play. Remove fiber blocks from between the gears
in the diffuser section. Rotate starter gear through at least one com-
plete revolution to see that it turns freely. If gear does not turn freely,
remove gear, separate the diffuser and rear crankcase sections. Check
matching bushings in diffuser and rear crankcase sections. When
bushings are properly alined and in serviceable condition, reinstall
diffuser section and proceed with assembly. Be sure to replace cover
over starter opening on rear Crankcase section.
m. Install Oil Pump. Lubricate oil pump thoroughly before in-
stalling it. Install new gasket over oil pump mounting studs at left
of rear crankcase section. Position pump over end of opening and
over studs. Make sure that pump drive gear is positioned to mesh
with accessory drive gear. Install washers over eight studs, and
202
TM 9-1725
75
1. Pushing Seal into Place 2. Installing Standpipe Seal
RA PD 314820
Figure 207 — Installing Standpipe Oil Seal
install eight attaching nuts. Start all nuts at one time, then tighten
them with wrench (41-W-1577-500), in order, until they are all
tightened securely. Insert cotter pins through nuts on the No. 1, 2,
and 3 studs. Fasten nuts together with lock wire on No. 4, 5, and 6
studs. Fasten nuts together with lock wire on No. 7, and 8 studs
(fig. 205).
n. Install Tachometer and Three-way Accessory Drive. Install
new gasket over studs arourid opening for tachometer and three-way
accessory drive. Position tachometer and three-way accessory drive
over studs with opening for three-way housing towards matching
opening in rear crankcase section (fig. 206). Install flat washers on
three studs, and castellated nuts over washers. Tighten nuts securely,
and fasten the three together with lock wire. Install tool for turning
accessory drive gear in end of right magneto coupling. Turn gear with
tool to make test operation of tachometer and three-way accessory
drive gear.
o. Install Tachometer Drive. Install new gasket over three studs
on right side of rear crankcase section. Position tachometer drive as-
sembly on studs. Install flat washer and castellated nut on each stud.
Tighten nuts securely, and fasten them together with lock wire.
Install tool for turning accessory drive gear in end of right magneto
coupling. Turn tachometer drive gear, and tachometer and three-way
accessory drive gear, to test operation of the gears.
203
Figure 210 — Tightening Crankshaft Gear Retaining Screws
p. Install Three-way Drive Housing. Install hew gasket over '
studs around opening for three-way drive gear in rear crankcase
section. Make sure that three-way drive gear is positioned to mesh
with tachometer and three-way accessory drive gear. Install housing
over studs. Install flat washers and retaining nuts on each of five
studs. ‘Tighten nuts securely. The studs for two of the washers and
nuts are inside the housing. Fasten the two nuts inside the housing
with cotter pins. Fasten the three nuts outside the housing together
with lock wire. Install new gasket over studs around spare drive open-
ing in three-way housing. Place cover over studs. Place flat washers
over studs and install nuts. Install sufficient flat washers over each
stud so that the castellations on the attaching nuts line up with the
safety wire hole in each stud. Tighten nuts securely, and fasten them
together with lock wire.
205
TM 9-1725
75-76
ORDNANCE MAINTENANCE - ORDNANCE ENGINE
MODEL R975-C4 (CONTINENTAL)
LOCK WIRE
Figure 211— Crankshaft Gear Attaching Cap Screws Secured
q. Install Oil Stand Pipe Seal. Place small, round, rubber seal
for oil standpipe around pipe (fig. 207). Using a valve push rod
socket as an installing tool, push seal down until seal is flush with face
of diffuser section (fig. 207).
r. Spread Sealing Compound on Flanges. Apply a thin coating
of sealing compound on matching flange of diffuser section.
s. Fill Gear with Oil. Fill the recess in all gears in the diffuser
section gear train with light engine oil (fig. 208). The recesses hold
approximately 1 quart of oil.
t. Cover Diffuser Section. Cover top of diffuser section to keep
out dust and dirt until ready for installation of main crankcase section.
76. MAIN AND FRONT CRANKCASE SECTIONS, ASSEMBLY
AND INSTALLATION.
a. Install Crankshaft and Master Rod Assembly. Place main
crankcase section on bench with opening for No. 9 cylinder at bottom.
Lubricate crankshaft rear journal. Lift assembly, and insert it in main
crankcase section with counterweights opposite the No. 8 "cylinder
opening .and the master rod pointing into the No. 1 cylinder opening
(fig. 209). Insert crankshaft assembly into crankcase section very
carefully, twisting it slightly so that the counterweights clear the open-
ing. Make sure that the rear main bearing journal enters the bearing
freely without forcing. If assembly is installed carelessly, the rear
main bearing may be damaged. Place crankshaft gear on end of
crankshaft so that holes in gear and crankshaft line up. Install eight
square-headed cap screws. Tighten screws securely (fig. 210).
206
Fasten screws with lock wire (fig. 211). Install protector for master'
rod on the No. 1 cylinder pad studs.
b. Install Main Crankcase Section. Spread a thin coat of sealing
compound on mounting flange of main crankcase section. Remove
covering from diffuser section. With the help of another person, lift
main crankcase section and position it over diffuser and rear crankcase
assembly, so that the sump drain openings in the main, diffuser, and
rear crankcase sections line up. Lower main crankcase sections over
rear crankcase section studs. Make sure that the oil standpipe enters
the standpipe hole in the main section. Be sure that the crankshaft
gear meshes with the starter and impeller drive gears before resting
the entire weight of the main section on the rear section flange.
Rotate crankshaft to mesh the gears (fig. 212).
c. Use of Lifting Eye. If lifting eye is available, assemble engine
by following procedure explained in paragraph 76, subparagraphs
a and f through o. When these steps have been completed, follow
207
TM 9-1725
76
ORDNANCE MAINTENANCE - ORDNANCE ENGINE
MODEL R975-C4 (CONTINENTAL)
Figure 213 — Securing Crankcase Mounting Stud Nuts
procedure prescribed in subparagraph b except to lift the front and
main crankcase sections for installation on the rear crankcase section
with lifting eye and hoist (fig. 70). Do not lift main crankcase section
with lifting eye attached to end of crankshaft, unless front crankcase
section and front thrust bearing have been attached to main crankcase
section. This operation might damage the rear main bearing by
placing too much weight on it.
d. Secure Main Crankcase Section to Rear Section. Place flat
washers on all rear crankcase section studs, except the four over which
ignition harness is attached (fig. 213). Install washers and mounting
nuts on studs. Using wrench (41-W-872-375), tighten each nut to
between 160 and 175 inch-pounds of torque (fig. 214). Secure mount-
ing nuts with lock wire. Leave ends of wire loose for attachment to
ignition harness mounting nuts (fig. 213). Securing rear crankcase
mounting nuts after installation of ignition harness is extremely diffi-
cult.
e. Install Ignition Harness. Loosen knurled nut securing two
sections of ignition harness shielding, to loosen the sections and make
installation easier. With open end of harness at bottom of main
crankcase section, position four bracket holes in harness over four igni-
208
TM 9-1725
76
ASSEMBLY OF SUBASSEMBLIES
Figure 214 — Tightening Main Crankcase Mounting Stud Nuts
Using Wrenches 41-W-872-375 and 41-W-3631
tion harness mounting studs in rear crankcase section (fig. 213).
Tighten knurled nut to secure 'wo sectio of harness shielding tightly
together. Install mounting nuts, but no flat washers, over ignition
harness studs. Tighten each nut to 450 inch-pounds, using same
wrenches used to tighten main crankcase section mounting nuts.
Secure ignition harness mounting nuts with lock wire left loose when
main crankcase section mounting nuts were secured.
f. Install Articulated Rods. Install articulated rods in pairs, the
rod for the No. 2 cylinder with the rod for the No. 3 cylinder; the
No. 4 rod with the No. 5 rod, etc. With the engine number stamped on
each rod facing up, position the No. 2 rod through the No. 2 cylinder
opening and between the flanges of the master rod. Position the No. 3
rod through the No. 3 cylinder opening in same way.
g. Install Knuckle Pins. Oil the bushing in each rod and the two
knuckle pins which will secure the rods to the master rod. With the
lock plate recess in the two knuckle pins facing each other (fig. 215),
insert knuckle pin for each, rod through the master rod flange and
into the articulated rod bushing. Line up knuckle pins so that screw
209
ORDNANCE MAINTENANCE - ORDNANCE ENGINE
MODEL R975-C4 (CONTINENTAL)
f — KNUCKLE PIN
ARTICULATED ROD
RA PD 314814
J ROD MARKING •
Figure 215 — Inserting Knuekle Pin
holes for lock plate line up with the lock plate screw holes in master
rod. Drive knuckle pins into place with a drift (fig. 216). Select
knuckle pin lock plate, and fit it between the knuckle pins, as all lock
plates must be a tight fit between the knuckle pins. Install knuckle
pin lock plates so screw holes line up with knuckle pin and master
rod lock plate screw holes. Install retaining plate over lock plate.
Install two cap screws in lock plate screw holes, and tighten them
securely. Bend thin retaining plate outer edges up against flat sides
of hexagon cap screws (fig. 217). Install rod protector for each
articulated rod on cylinder hold-down studs. Install remaining articu-
lated rods in pairs by same method. NOTE: Be sure to install rod
protector on each rod after installation.
h. Install Front Main Bearing. If bearing inner race was re-
moved during disassembly, position bronze inner spacer on crank-
shaft with radius down (fig. 218). Heat bearing inner race to approxi-
mately 250°F. Position inner race over crankshaft with bearing
210
PUNCH
E PINS v - ARTICULATED RODS RA PD 314813
Figure 216 — Driving in Knuckle Pin
. r— SCREWS FOR KNUCKLE PIN LOCK.
RA PD 314812
ig Plate
RA PD 314811
RA PD 314810
Figure 218 — Installing Front Figure 219 — Installing Front
Main Bearing Spacer Main Bearing Inner Race
flange down (fig. 219). Shoulder flange against spacer. Check bear-
ing outer race to see that rollers are in place and are properly lubri-
cated. Lower outer race and rollers onto inner race. Push rollers
back into outer race so that race will drop into position against flange
of inner race (fig. 220). Lower outer spacer into position over crank-
shaft (fig. 221).
i. Install Front Main Bearing Support. Apply a thin coat of
sealing compound to matching surface of front main bearing support
(fig. 222). Position support over main crankcase section so that
sump connection cut-out in support matches sump connection cut-out
in main section (fig. 223). Lower support over main section studs.
Tap support evenly all around with soft hammer until it seats posi-
tively against main crankcase section.
j. Install Thrust Bearing Spacer. With either end down, place
thrust bearing spacer over crankshaft (fig. 224). Spacer controls
clearance between crankshaft rear crank and rear main bearing.
k. Install Crankcase Front Section. Apply a thin coat of seal-
ing compound to matching flange of front crankcase section (fig. 222).
Position front crankcase section over main crankcase section by point-
ing breather connection in front section directly towards No. 1 cyl-
212
TM 9-1725
76
ASSEMBLY OF SUBASSEMBLIES
Figure 22 0 — Installing Front Figure 221 — Installing Spacer
Main Bearing Outer Race on Top of Front Main Bearing
and Rollers
inder opening in main section. Lower front section over main crank-
case section studs. Tap front crankcase section all around with soft
hammer to insure positive contact of matching flanges.
l. Install Front Thrust Bearing. With markings on front thrust
bearing facing up, place bearing over crankshaft. Using driver, drive
bearing into recess in front crankcase section (fig. 225). Install flat
washers over main crankcase section mounting studs, and install
mounting nuts. Tighten mounting nuts securely and evenly, and
secure with lock wire. Tighten lock wire by method shown in figure
226. Install front cover section laminated shim over front crank-
case section mounting studs and dowel (fig. 227). Place front cover
in position over studs and against shim.
m. Check Front Cover Clearance. Check clearance between front
cover and front crankcase section (fig. 228) with feeler gage. Clear-
ance should measure 0.004 inch, so that when the cover is tightened
down, it will hold the crankshaft thrust bearing securely in place.
If clearance is less than 0.004 inch, remove cover and install new
laminated shim. Peel off shim laminations until proper clearance is
obtained. If clearance is greater than 0.004-inch, peel off shim
laminations until correct clearance is obtained. CAUTION: When
213
-WASHERS-
STUD NUTS-
- SUPPORT BAR CLAMP
RA PD 314700
Figure 222 — Front Main Bearing Support, Front Crankcase
Section, and Cover — Disassembled
FRONT MAIN BEARING. Ill I 1(1 -w
SUPPORT —i II I k I JC
CUT-OUT FOR SUMP CONNECTION
A
zl
RA PD 314806
Figure 223 — Installing Front Main Bearing Support
removing shim laminations, be sure to remove a complete lamination,
not just a portion of it.
n. Install Front Thrust Nut. Lubricate thrust nut oil seal rings
in grooves on thrust nut. Place thrust nut over end of crankshaft.
214
TM 9-1725
76-77
ASSEMBLY OF SUBASSEMBLIES
SUPPORT RA PD 314807
Figure 224 — Installing Thrust Bearing Spacer
Install special ring compressor on rings and compress them. Secure
thrust nut in recess in front cover by holding rings compressed and
turning thrust nut on crankshaft threads (fig. 229). Turn nut until
oil seal rings are compressed below surface of cover. Remove ring
compressor. Using special wrench (fig. 59), and holding crankshaft
from turning, tighten thrust nut very securely.
o. Secure Front Section Cover. Install flat washers over front
crankcase section studs. Place attaching nuts on studs. Tighten nuts
from 225 to 250 inch-pounds of torque.
p. Check Crankshaft End Clearance. Measure crankshaft clear-
ance between rear crank and edge of rear main bearing with feeler
gage (fig. 231). If clearance is less than 0.025 inch, disassemble
front crankcase section, and grind off one end of thrust bearing spacer.
If clearance is more than 0.045 inch, disassemble front crankcase
section, and replace thrust bearing spacer. Reassemble front crank-
case section, and recheck crankshaft clearance to make sure it falls
between allowable limits. Secure attaching nuts with lock wire in
groups of two, two, and three. Install split bronze cone on end of
crankshaft.
77. CYLINDER, VALVE, AND VALVE OPERATING MECHA-
NISM INSTALLATION.
a. Prepare Engine for Cylinder Installation. Install timing bar
on front end of crankshaft. Hang nine new cylinder barrel rubber
215
Figure 225 — Installing Front Thrust Bearing
seals on timing bar (fig. 232). Identifying cylinders by numbet
stamped on front of rocker boxes, select the No. 1 cylinder assembly
Clean assembly. Install rear spark plug, and tighten it from 450 to
480 inch-pounds of torque. Oil cylinder bore. Remove cylinder bar-
rel-seal from timing bar, and place it around base of cylinder against
barrel flange. Place assembly on bench until ready to install in
engine.
b. Install No. 1 Piston. Turn engine with timing bar until master
rod is at top center. Remove master rod protector. Clean the No. 1
piston, piston pin, and piston retaining plugs in dry-cleaning solvent.
Dry them with compressed air. Lubricate piston pin and the piston
pin bushing in master rod. Place piston over master rod, and install
216
TM 9-1725
77
ASSEMBLY OF SUBASSEMBLIES
Figure 22 6 — Securing Front Crankcase Section
LAMINATED SHIM-i «
Figure 227 — Installing Laminated Shim for Front Cover
piston pin. Install piston pin retaining plugs in ends of piston pin.
Hold bottom plug in position, and install ring compressor (41-C-2550-
80) over piston rings (fig. 232). Compressor will hold retaining
plugs in position until cylinder is installed.
c. Install No. 1 Cylinder. Holding cylinder in one hand and
compressor on piston assembly with the other, slide cylinder straight
over piston assembly (fig. 232). Do not rock cylinder up and down
to install it. Remove piston ring compressor as it is forced off piston
skirt. Holding cylinder, install eight cylinder hold-down nuts on
cylinder hold-down studs. Tighten nuts to 450 inch-pounds of torque
217
TM 9-1725
77
ORDNANCE MAINTENANCE - ORDNANCE ENGINE
MODEL R975-C4 (CONTINENTAL)
HA PD 314789
Figure 228 - Checking Clearance at Front Cover Using
Gage 41-G-400
RA PD 314791
Figure 22 9 — Installing Front Thrust Nut
218
TM 9-1725
77
ASSEMBLY OF SUBASSEMBLIES
Figure 23! — Checking Clearance Between Crankshaft and Rear
Main Bearing Using Cage 41-G-400
(fig. 233). Secure nuts in pairs with lock wire at this time. It is
much easier to secure nuts as each cylinder is installed than after all
cylinders are installed. Install screened breather plug in front spark
plug hole (fig. 234).
d. Install Remaining Pistons and Cylinders. Install each re-
maining piston and cylinder following procedures explained in sub-
paragraphs b and c above. Install pistons and cylinders in numerical
order, one, two, three, four, etc. Be sure to remove rubber seal from
timing bar, and place over each cylinder barrel against flange before
installing cylinder. Before installing each cylinder, turn crankshaft
so that articulated rod for the cylinder being installed is at top center.
219
TM 9-1725
77
ORDNANCE MAINTENANCE - ORDNANCE ENGINE
MODEL R975-C4 (CONTINENTAL)
^ CYLINDER BARREL OIL SEALS — v
7 ■ A. mWm
No. 1 CYLINDER RING COMPRESSOR RA PD 314803
Figure 23 2 — Installing No. I Cylinder Using Fixture 4 1 -F -2997 -84
and Compressor 41-C-2 550-80
After installing the No. 2 cylinder, loosen and back off spark plug
conduit nut from harness end of spark plug conduit wire between
the cylinders. Double up conduit wire, and push wire up between
base of the cylinders. Tighten conduit nut. After each cylinder is
installed, repeat the procedure of pushing spark plug conduit wire be-
tween cylinders. _ Check all cylinders after they are installed to see
that no rubber seals remain hanging on timing bar as proof that seal
has been installed on each cylinder.
e. Install Intercylinder Air Deflectors. Position engine for easy
accessibility. Select the proper intercylinder air deflector, and insert
it through rear of engine, between proper pair of cylinders, and over
cylinder exhaust elbows. Thread hooked end of deflector attaching
spring through to front of cylinders as deflector is installed. Air de-
flectors installed between the Nos. 6 and 7, and Nos. 4 and 5 cylinders,
have openings for two spark plug conduits. The air deflector in-
stalled between the Nos. 5 and 6 cylinders has a large opening for
the sump front drain tube. The air deflector installed between the
Nos. 7 and 8 cylinders has no opening. Air deflectors installed be-
tween the Nos. 3 and 4, 2 and 3, 1 and 2, 9 and 1, and 8 and 9 cyl-
inders, have an opening for a single spark plug conduit. Make sure
220
TM 9-1725
77
ASSEMBLY OF SUBASSEMBLIES
TM 9-1725
77
ORDNANCE MAINTENANCE - ORDNANCE ENGINE
MODEL R975-C4 (CONTINENTAL)
LOCK NUT
ROCKER ARM
ASSEMBLY
VALVE
TAPPET
TAPPET
ROLLER PIN
RA PD 314691
Figure 2 35 — Valve Operating Mechanism
222
TM 9-1725
77
ASSEMBLY OF SUBASSEMBLIES
that spark plug conduits are in opening provided in intercylinder air
deflectors.
£. Install and Connect Spark Plugs. Make sure there is a solid
copper gasket on each spark plug. Do not use a gasket less than
0.068 inch thick. A thinner gasket allows plug to be screwed in too
far exposing threads to gases in combustion chamber and causing
preignition. Install plugs, and tighten them with torque wrench con-
nected to 1-inch socket wrench. Tighten each spark plug from 450
to 480 inch-pounds of torque. Remove protectors from spark plug
cigarette connectors. Insert cigarette connector into spark plug.
Tighten conduit lock nuts at both ends of each elbow connector. In-
stall and connect remaining rear plug.
g. Install Fuel Induction Tubes. Check tubes to make sure
that gland nut and new rubber seal are positioned properly on one
end of each induction tube. Insert nut, and seal end of tube in re-
cess in rear crankcase section (fig. 6). Push seal and nut into recess,
and start nut on recess threads. Tighten nut finger-tight. Install
new gasket between cylinder head and induction tube flange.
h. Install Cylinder Head Air Deflectors. Install cylinder head
air deflector on cylinder head. Air deflectors are interchangeable
with the exception of the one with the long Dzus fasteners (marked
200 on head). This deflector is installed on the No. 7 cylinder head.
The long fastener is used to fasten air deflector to cowling. Install
flat washers and lock washers on each of three attaching cap screws.
Install three cap screws in holes in induction tube flange. Upper
cap screw also attaches air deflector to cylinder head. Tighten cap
screws to secure tube to cylinder head. Using special wrench (41-W-
1537), tighten induction tube gland nut in rear crankcase section
recess. Install remaining induction tubes and cylinder head air
deflectors in same way.
i. Install Push Rod Housings. Lubricate push rod springs and
sockets. Install a spring and socket in valve tappet guide by placing
them through opening in push rod housing adapters in each cylin-
der. Install push rod housing connecting hose. Position one hous-
ing, with its connecting hose and clamps, between the push rod hous-
ing adapter on the main crankcase section, and the push rod housing
on the cylinder rocker box. Place the end with the hose with the
single small clamp, nearest the rocker box push rod housing adapter.
Slide hose at other end of housing over main crankcase housing
adapter, and tighten hose clamps with wrench (41-W-1986). Place
push rod housing up against rocker box push rod housing adapter,
and slide hose over end of adapter. Tighten two hose clamps. In-
stall remaining housings in same way.
223
TM 9-1725
77
ORDNANCE MAINTENANCE - ORDNANCE ENGINE
MODEL R975-C4 (CONTINENTAL)
Figure 236 — Rocker Arm Assembly — Disassembled
j. Install Push Rods. Lubricate each push rod (fig. 235) and in-
stall them, one at a time, through rocker box and into push rod hous-
ing (fig. 47). Push each rod against push rod spring and socket
(fig. 235) to test the spring action, to make sure the push rod end is
properly seated in the socket, and that the socket is in position in
valve tappet guide. Install each push rod in same way.
k. Install Rocker Arms. Check to see that the No. 1 cylinder
valves are closed. If they are not, turn timing bar and close them.
Back off rocker arm tappet adjusting screws in all rocker arms, and
lubricate bearings in the intake rocker arm (fig. 236). Position intake
rocker arm between bosses in intake rocker box. Place rocker arm
hub bolt washer on bolt. Install bolt through rocker box and rocker
arm. Place rocker arm hub bolt nut washer over end of bolt, with
washer recess facing outward so that rocker arm hub bolt nut fits into
washer recess. Install and tighten nut to from 250 to 325 inch-pounds
of torque (fig. 46). Safety nut with cotter pin. Install exhaust rocker
arm, and install rocker arms for remaining cylinders in same way.
Be sure that cylinder valves are closed at all times. After all rocker
arms have been installed, give the clearance between rocker arm
rollers and valve stems an approximate setting by turning adjusting
screw on each rocker arm. This is to assist in holding the cam ring in
position for valve timing later in the assembly. Install intercylinder
air deflector brackets between the eleventh and twelfth fin of each
224
ASSEMBLY OF SUBASSEMBLIES
TM 9-1725
77
Figure 237 — Timing Engine Using Indicator 41-1-73-100 and
Fixture 41 -F-2997-84
225
TM 9-1725
77
ORDNANCE MAINTENANCE - ORDNANCE ENGINE
MODEL R975-C4 (CONTINENTAL)
ROCKER ARM FOR
No. 1 EXHAUST VALVE— y f %
RA PD 314797
Figure 238 — Checking Valve Action
cylinder, counting up from the base of the cylinder (fig. 42). Attach
intercylinder air deflector springs to air deflector brackets (fig. 41).
1. Set Timing Disk Pointer. If timing bar, or disk, is not in-
stalled, install it at this time on front end of crankshaft. Install timing
disk pointer on front cover top hold-down stud. Install top dead
center indicator (41-1-73-110) in No. 1 cylinder spark plug hole
(fig. 237). Set pointer so that it points as closely as possible to
226
TM 9-1725
77
ASSEMBLY OF SUBASSEMBLIES
Figure 2 39 — Adjusting Valve Clearance Using Gage 4I-G-4I2-75
center of No. 1 cylinder. Turn crankshaft in counterclockwise direc-
tion (as viewed from front) until, on upstroke of piston, top dead
center (TDC) indicator reads zero. Note the reading on the timing
disk as indicated by the pointer. Continue to turn crankshaft in same
counterclockwise direction until the pointer on the top dead center
indicator has gone past and returned to zero. Again note the reading
on the timing disk. Turn the crankshaft backwards (clockwise)
about one-quarter of a revolution then turn it forward (counterclock-
wise) until the timing disk pointer indicates a point on the timing
disk exactly midway between the two readings previously obtained.
Then adjust the pointer to indicate exactly zero degree on the timing
disk. Leave the pointer in this position. Remove top dead center
indicator.
m. Time Valves.
(1) Adjust No. 1 Cylinder Valve Clearance. Turn crank-
shaft in a counterclockwise direction until the No. 9 intake valve
just begins to open (fig. 238). Tap push rod ends of both No. 1
cylinder rocker arms with fiber mallet. Adjust valve tappet clearance
between the rocker arm roller and valve stem for the No. 1 cylinder
intake and exhaust valves by turning rocker arm adjusting screw in or
out until a clearance of 0.070 inch is obtained. Measure clearance
with feeler gage (fig. 239). Wash grease from hands, and from rocker
arm rollers with dry-cleaning solvent. Press rocker arm adjusting
227
TM 9-1725
77
ORDNANCE MAINTENANCE - ORDNANCE ENGINE
MODEL R975-C4 (CONTINENTAL)
STARTER OPENING — 7 STARTER SHAFT BOLT— 1 ' LOCK NUT
RA PD 314798
Figure -240 — Disengaging Timing Serrations
screw for the No. 1 cylinder intake valve down, with the fingers of
your right hand, and turn rocker arm roller with thumb. At the
same time, turn crankshaft in counterclockwise direction until roller
begins to bind (fig. 238). Loosen lock nut at rear end of starter
shaft bolt. Insert screwdriver in bolt slot to keep bolt from turning.
Push bolt forward to disengage timing serrations at front end of bolt
from serrations in starter gear (fig. 240). While holding bolt in this
forward position, turn crankshaft until timing disk pointer registers
eight degrees before top dead center on timing disk. Permit bolt to
slip back and reengage timing serrations with serrations on starter gear.
Tighten bolt lock nut securely; then back off nut V 2 turn. With
screwdriver in bolt slot, attempt to rotate starter shaft bolt to make
sure bolt serrations are meshed with starter gear serrations. Retighten
lock nut.
(2) Adjust Clearances for Other Valves. Adjust clearance
between rocker arm rollers and valve stems on all other cylinders in
same way, but to only 0.006 inch. Set the valve tappet clearances
first on the odd numbered cylinder assemblies, in order, beginning
with No. 3; then on the even numbered assemblies beginning with
No. 2. When adjusting valve tappet clearance for each valve assem-
bly, be sure to turn crankshaft so top dead center marking on timing
228
TM 9-1725
77-78
ASSEMBLY OF SUBASSEMBLIES
bar points towards the center of the cylinder on which clearance is
being adjusted. After adjusting clearance for each valve, tighten
adjusting screw lock nut. After valve tappet clearances have been
adjusted, check valve timing again.
(3) Recheck Valve Timing. Turn crankshaft until the No. 1
cylinder intake valve begins to open. The valve should start to open
at 8 degrees plus or minus 4 degrees, before top dead center, as indi-
cated on the timing disk by the timing disk pointer. Turn crankshaft
until No. 1 cylinder exhaust valve starts to close. Exhaust valve
should start to close at 19 degrees plus or minus 4 degrees as indicated
on the timing disk by the timing disk pointer. Turn crankshaft until
the No. 1 cylinder is- at top dead center on the compression stroke.
Adjust No. 1 cylinder valve clearance to 0.006 inch by procedure
explained above. Leave timing disk pointer in position for magneto
timing.
n. Install Rocker Box Covers. Install new gaskets on all rocker
box mounting flanges. Place rocker box covers over rocker box
studs. Place flat washers, lock washers, and nuts over studs. Tighten
nuts securely. Rocker box covers for the Nos. 3 and 4, 4 and 5, 6 and
7, and 7 and 8 cylinders (cylinders on the lower side of the engine)
are connected in pairs by drain tubes. Install the joined box covers
together.
78. ACCESSORIES AND MISCELLANEOUS SUBASSEMBLIES,
INSTALLATION.
a. Install Generator. Remove two nuts which secure cover over
opening in generator support in rear crankcase section, and remove
cover. Place new gasket over generator support pad studs. With
data plate facing up, position generator over support pad studs
with generator splined drive fitting into splined opening in support
pad. Place flat washers over studs, and install castellated nuts on
studs. Using special wrench (41-W-636-550), tighten nuts securely
(fig. 32). Secure nuts in pairs with lock wire.
b. Install and Time Magnetos.
(1) Install and Time Right Magneto. Turn crankshaft in
counterclockwise direction until timing pointer and disk indicate 29
degrees before top dead center on the compression stroke of the No. 1
cylinder. Do not turn the crankshaft beyond the 29-degree indication
and then turn it back. If this is done, the backlash of the gears will
throw the magneto out of timing. Check the matching surfaces of
the right magneto mounting flange and mounting pad to make sure
they are clean. Apply rust preventive to magneto drive gear splines.
Position magneto in front of magneto mounting pad. Turn magneto
splined drive until two marks engraved on large distributor gear line
up with corresponding marks on front end cover plate. Install mag-
neto over mounting pad studs with magneto splined drive entering
magneto coupling on right accessory drive shaft. Move magneto on
229
TM 9-1725
78
ORDNANCE MAINTENANCE - ORDNANCE ENGINE
MODEL R975-C4 (CONTINENTAL)
studs by means of elongated slots on magneto mounting flange, until
the large distributor gear marks are exactly opposite front end cover
plate marks. Use a straightedge to obtain an accurate alinement of
the marks. When the marks line up, the mounting pad studs should
be in the approximate center of the elongated slots. If they are not,
remove magneto from mounting studs. Turn large distributor gear
one complete revolution until marks on gear and cover plate again
line up. This operation changes the position of the magneto drive
splines, and will bring the mounting pad studs in the approximate
center of the elongated slots on the magneto mounting flange, when
the magneto is reinstalled on the mounting pad. Having the studs
in the approximate center of the elongated slots, provides sufficient
range for final timing of the magneto during the engine test run.
Install washers and nuts on mounting studs, and tighten nuts. Secure
nuts with lock wire.
(2 ) Install and Time Left Magneto. Turn crankshaft counter-
clockwise 3 degrees from the 29-degree point. The pointer will indi-
cate 26 degrees before top dead center on the timing disk. Follow
the procedure used in subparagraph b ( 1 ) to install and time the left
magneto.
(3) Install Magneto Distributor Blocks. Connect one mag-
neto ground wire to right magneto by screwing terminal end into
opening provided in top of magneto. Connect other ground wire
to left magneto by same method. Connect secondary booster coil wire
to right magneto by following the same procedure. Push rubber
grommets down on' magnetos. Install magneto distributor blocks to
each magneto.
(4) Install Distributor Block Covers. Position matching
halves of distributor block cover on right magneto (fig. 31). Covers
are marked on the inside. Match up covers similarly marked. Se-
cure the bottoms of the covers to the magnetos with clamps. Install
safety pin in each clamp. Squeeze covers together at the top.
Install bolts through matching holes on either side at top cover halves.
Place flat washers, lock washers, and nuts on ends of bolts. Tighten
nuts. Place flat washers and lock washer on each of two cap screws
which hold shielding elbow to top half of each cover. Install and
tighten cap screws. Tighten knurled nut on harness connection to
magneto elbow. Install distributor block cover on left magneto in
same way, and tighten knurled nut on harness connection to magneto
elbow (fig. 27).
c. Install Starter. Remove cover plate from opening on starter
mounting pad in rear crankcase section. Place new gasket over
mounting pad studs. Position starter over studs with cranking unit
at top. Install plain washers and hold-down nuts on six studs. Using
230
231
WASHER
TM 9-1725
78
ORDNANCE MAINTENANCE - ORDNANCE ENGINE
MODEL R975-C4 (CONTINENTAL)
r RUBBER SEAL
FRONT DRAIN
TUBE
ROCKER BOX
DRAIN TUBE
ADAPTER
FITTING TO MAIN CASE.
RUBBER SEAL
SPIDER ASSEMBLY
ROCKER BOX
DRAIN TUBE
TANK
RA PD 314842
Figure 242 — Sump — Disassembled
232
ASSEMBLY OF SUBASSEMBLIES
-FLAT WASHERS
-CAP SCREWS
TM 9-1725
78
RUBBER
SEAL-
SPECIAL \
WASHER A
RA PD 314851
Figure 243 — Sump Drain Tube — Disassembled
special wrench (fig. 30), tighten nuts, and secure them with lock wire
in groups of three and three. Place starter-generator support bracket
side plates in position between starter and generator. Install flat
washers on eight nuts that attach side plates to support bands. Install
and tighten nuts. Secure each nut with cotter pin (fig. 29).
d. Install and Connect Front Spark Plugs. Follow procedure
for installing and connecting rear spark plugs (par. 77 f).
e. Install Engine Cowling. Position cowling so that the holes in
the engine front support bar clamp and cowling, and the holes in
cowling bracket line up with bolt holes in cylinder rocker boxes. Bend
intercylinder and cylinder head baffles back to make sure they are on
outside of cowling. Install bolts through rocker box bolt holes and
cowling. Place flat washers and nuts on bolts. Tighten nuts and
secure with cotter pin. Secure cowling to intercylinder and cylinder
head baffles by tightening Dzus fasteners. There are two Dzus fas-
.teners in each intercylinder baffle, and three in each cylinder head
baffle.
f. Install Engine Front Support Bar. Slide bar through hole in
either side of cowling, and through support bar center clamp at front of
engine (fig. 36). Center the bar so that it extends an equal distance?
on each side of clamp. Install 10 stud nuts on support bar center
clamp, 5 below and 5 above. Tighten nuts, and secure them with
lock wire, 5 and 5.
g. Install Sump.
(1) Install Sump Spider (fig. 242). Install new rubber gasket
over end of sump fitting in bottom of main crankcase section. Install
new gasket on machined face in end of spider. Slide end of spider
assembly over sump fitting. Place washer in spider plug and screw
plug onto bottom of spider assembly fingertight. Position spring,
washer, and seal on end of drain tube (fig. 242). Working from front
of engine, install drain tube between cylinder baffles and into spider.
233
Figure 2 44 — Primer Distributor and Lines — Installed
Install new gasket between end of drain tube and drain tube opening
in main crankcase section. Install flat washers on two cap screws
which secure drain tube to main crankcase. Install screws and
tighten. Secure screws together with lock wire.
(2) Install Sump Tanks (fig. 243). Place new gaskets for oil
tube fittings over studs on each oil sump tank. Position tank assem-
bly so that rocker box drain tube fitting studs on tanks pass through
holes in fitting, and the holes in sump tank brackets fit over mounting
studs on the Nos. 5 and 6 cylinder heads. Install flat washers and
castellated nuts on rocker box drain tube fitting studs. Tighten nuts
and secure them in pairs with lock wire. Attach three connecting
pipes from sump spider assembly to each sump tank and to strainer
234
TM 9-1725
78
ASSEMBLY OF SUBASSEMBLIES
Figure 245 — Exhaust Collector Ring
housing, by means of three attaching hose fitted over the pipes and
sump tank and strainer housing connections. Tighten hose with
hose clamps at each end of the hose. Install lock washers and nuts
on rocker box mounting studs. Tighten nuts, and bend lock washer
against flat side of hexagonal nuts. Tighten spider plug securely at
this time and safety with lock wire.
h. Install Crankcase Breather. Install hose clamps over both
ends of hose connecting crankcase breather to rear and main crank-
case sections (fig. 44). Install one end of each hose over hose con-
nections on breather. Install breather on engine with bolt holes in
breather bracket lined up with bolt holes in No. 1 cylinder rocker
boxes. Install two bolts. Place flat washers, nuts, and palnuts on
bolts. Tighten nuts and hose clamps.
i. Install Primer System. Place rear half of primer attaching
bracket behind fuel induction tube for the No. 1 cylinder (fig. 43).
Position primer distributor assembly over induction tube so that
holes in front half of bracket line up with holes in' rear half of bracket.
Place washers on cap screws, install cap screws in bracket holes, and
235
TM 9-1725
78
ORDNANCE MAINTENANCE - ORDNANCE ENGINE
MODEL R975-C4 (CONTINENTAL)
GASKET— j
GOVERNOR-, /
GOVERNOR LINKAGE
WASHER
i
CARBURETOR MOUNTING
BOLTS
CARBURETOR ELBOW
THROTTLE BOX MOUNTING
STUDS
GASKET
THROTTLE BOX MOUNTING
WASHERS AND STUD NUTS
THROTTLE BOX
GASKET
CARBURETOR SUPPORT
BRACKET
CARBURETOR
AIR HORN
RA PD 314782
Figure 246 — Carburetor, Governor, and Related Parts
— Disassembled
236
TM 9-1725
78
ASSEMBLY OF SUBASSEMBLIES
Figure 247 — Installing Fuel Pump
tighten. Fasten screws with lock wire. Connect each primer line to
cylinder head elbow (fig. 244). Place primer line clamps around each
fuel induction tube, and tighten clamps to secure lines to induction
tubes. Attach engine sling to rocker box arm hub bolts and remove
engine from stand.
j. Install Exhaust Collector Ring (fig. 245). With engine sus-
pended from sling, install new copper gaskets on cylinder exhaust
elbows. Position Collector ring segments so that ring stud mounting
holes fit over two studs in each cylinder exhaust elbow. Install
washers and nuts on studs, and tighten nuts securely. Fasten two
nuts on each exhaust elbow together with lock wire.
k. Install Engine Rear Support. Position rear engine support
ring on rear of engine with flat side towards engine (fig. 3). Line up
bolt holes in engine and support ring. Remove bolts, nuts, and
washers, from bolt holes in engine mounting stand. Install bolts, and
place washers and nuts on bolts. Tighten nuts from 400 to 425 inch-
pounds of torque. Secure nuts with cotter pins. Secure support to
suitable engine stand. Remove engine sling from rocker arm hub
bolts.
l. Install Governor (fig. 246). Remove cover from governor
drive flange opening in oil pump. Place new gasket over studs
around drive flange opening. Position governor over studs. Install
washers, plain nuts, and palnuts on studs. Tighten nuts.
m. Install Carburetor Elbow (fig. 246). Place new gasket over
237
TM 9-1725
78
ORDNANCE MAINTENANCE - ORDNANCE ENGINE
MODEL R975-C4 (CONTINENTAL)
carburetor elbow mounting studs in rear crankcase section. Position
elbow over studs. Install washers and nuts over studs. Tighten nuts
and secure them with lock wire.
n. Install Throttle Box (fig. 246). Place new gasket on top
mounting flange of throttle box. Install throttle box over carburetor
elbow studs. Place washers and nuts on four studs, and tighten nuts.
Fasten nuts in pairs with lock wire. Before installing throttle box
linkage to governor, be sure there is tension on the governor spring.
Attach link to governor arm. Adjust link so link pin fits freely into
throttle box arm. Lengthen link one-half to one turn, and insert
clevis pin and cotter pin. Make certain that linkage fits freely and
does not have to be bent into alinement with governor and throttle
arm.
o. Install Carburetor Support Bracket (fig. 246). Place new
gasket between carburetor support bracket and throttle box. Position
support bracket so bracket cap screw holes line up with holes in rear
crankcase section. Install washers on two cap screws. Install cap
screws through bracket holes and rear crankcase section holes.
Tighten screws, and fasten them together with lock wire.
p. Install Carburetor (fig. 246). Install four carburetor attach-
ing bolts through holes in throttle box bottom flange and bolt holes
in support bracket. Place new gasket on carburetor mounting flange.
Install carburetor over attaching bolts. Place flat washers and self-
locking' nuts on four bolts, and tighten nuts.
q. Connect Conduit to Carburetor (fig. 12). Remove cap from
degasser unit. Remove nut, lock washer, and flat washer from ter-
minal post. Remove from bench wire which runs from degasser
unit to control on vehicle. This wire has a conduit on it. Slip wire
terminal over terminal post. Install washer, plain lock washer, and
nut, on terminal post, and tighten nut. Replace and screw upper
cap on degasser unit (fig. 12). Slip conduit up on conduit elbow,
and tighten elbow nut. Install clip which holds loose end of conduit
to rear engine support until ready to install in vehicle.
r. Install Fuel Pump. Install fuel pump drive gear in square
adapter on drive gear shaft. Install new gasket over four fuel pump
mounting pad studs on three-way-accessory drive housing. Install
fuel pump and fuel pump adapter elbow as a unit over studs. In-
stall enough washers on each stud to bring castellated nuts in line
with lock wire holes in studs. Install castellated nuts on studs.
Tighten nuts, and fasten in pairs with lock wire.
s. Install Fuel and Drain Lines (fig. 11). Install hose and
clamps over fittings on fuel pump and carburetor. Tighten clamp
at each end of hose. Connect drain line running from governor to
238
TM 9-1725
78-79
ASSEMBLY OF SUBASSEMBLIES
fuel pump adapter elbow. Connect drain line running from fuel
pump adapter elbow to’ sump.
t. Install Booster Coil (fig. 28).
(1) Install Booster Coil. Line up booster coil bracket over
holes on right side of rear engine support. Install toothed lock
washers on fillister head screws. Install screws in matching holes in
booster coil mounting flange and engine support. Tighten screws.
(2) Install Connections. Uncoil primary booster coil wire
attached to booster coil. Slide conduit to booster coil over wire, and
secure conduit to booster coil. String wire through right magneto
elbow from right to left. Tighten knurled nut attaching conduit to
right magneto elbow. Uncoil booster coil secondary wire attached
to right magneto elbow. Slide conduit over wire. Attach conduit
elbow to right magneto elbow by tightening hexagonal nut. Install
cigarette connector on secondary booster coil wire, and bend over
ends of wire to secure cigarette connector to wire. Attach cigarette
end of secondary booster coil wire to booster coil. Uncoil ground
wire to right magneto elbow. Slide intermagneto elbow conduit
over primary booster coil wire and right magneto ground wire.
Run these two wires through left magneto elbow from right to left.
Secure conduit to two magneto elbows by tightening hexagonal nut
at each end. Uncoil left magneto ground wire left in coil. Slide
the conduit, which runs from left magneto elbow to vehicle, over
the three wires. Attach conduit to left magneto elbow by tightening
knurled nut. Solder terminals to wire ends.
79. FLYWHEEL, FAN, AND CLUTCH INSTALLATION.
a. Install Rear Cone. Making sure flat surfaces are clean and
free from burs, install rear brass cone on engine crankshaft (fig. 248).
b. Install Flywheel and Fan. Wipe inner and outer cones of fly-
wheel clean. Lift assembly, and install over crankshaft. Crankshaft
hub and flywheel hub are splined so assembly will go only one way.
c. Install Front Cone and Nut. Place two halves of front cone
in position over flange of front cone nut (fig. 249). Hold nut in posi-
tion in flywheel hub, and screw nut up by hand as far as possible.
d. Tighten Cone Nut. Place a wood block between ventilating
opening in flywheel and stand (fig. 249). Insert %-inch diameter
bar through holes in nut, and tighten nut from 600 to 650 foot-
pounds of torque.
e. Lock Nut into Position. Insert retaining pin from inside
through opening in crankshaft and in nut. Install flat washer over
pin. Install and secure cotter pin (fig. 249).
f. Install Separator Pins. Install driving plate separator pins by
inserting small end of pin in holes in flywheel (fig. 250). Press in
239
TM 9-1725
79
ORDNANCE MAINTENANCE - ORDNANCE ENGINE
MODEL R975-C4 (CONTINENTAL)
TM 9-1725
79
ORDNANCE MAINTENANCE - ORDNANCE ENGINE
MODEL R975-C4 (CONTINENTAL)
FLYWHEEL
HOLE FOR PIN
DRIVING PLATE
SEPARATOR PIN
DRIVING PLATE
SEPARATOR PINS
1 . INSTALLING DRIVING PLATE SEPARATOR PINS
3. INNER DRIVEN DISK IN POSITION
Figure 250 — Installing Inner Driven Disk
242
RA PD 53594
TM 9-1725
79
ASSEMBLY OF SUBASSEMBLIES
0.015-0.018 IN.
CLEARANCE AT
THIS POINT AT
EACH DRIVING PIN
RtV
DRIVING PLATE
FLYWHEEL
DRIVING
PIN
PUNCH MARKS
Figure 251 — Installing Driving Plate
RA PD 314869
against each pin as it is installed to test spring tension. Make sure
pins each return to normal position when pressure is released.
g. Install Spindle. Place spindle in position on hub of flywheel
(fig. 250).
h. Install Inner Driven Disk. With long end of the hub section
facing out, or towards operator, install inner, driven disk on spindle
(fig. 250).
i. Install Driving Plate. Line up prick punch marks on fly-
wheel and driving plate. Install driving plate over spindle, and over
the six flywheel driving pins (fig. 251). Check clearance between
flywheel driving pins and driving plate. If the clearance is not be-
tween 0.015 and 0.018 inch on the drive side of each flywheel driv-
ing pin, remove driving plate, and file recesses until proper clearance
is obtained (fig. 251).
j. Install Outer Driven Disk. With long end of the hub section
facing out, or towards operator, place outer driven disk in position on
spindle.
k. Install Flywheel Ring and Pressure Plate. Using a lifting
eye, or with the help of another person, install flywheel ring and pres-
sure plate on spindle (fig. 252). Be careful flywheel ring bolts are
not pushed back out of position in flywheel when positioning pressure
plate assembly. Place nuts on 12 bolts, and tighten uniformly to
between 75 and 85 foot-pounds of torque (fig. 252).
243
TM 9-1725
79
ORDNANCE MAINTENANCE - ORDNANCE ENGINE
MODEL R975-C4 (CONTINENTAL)
FLYWHEEL -
FLYWHEEL TO FLYWHEEL
RING BOLT
FLYWHEEL RING AND
PRESSURE PLATE ASSEMBLY
1. INSTALLING FLYWHEEL RING AND PRESSURE PLATE ASSEMBLY
FLYWHEEL TO FLYWHEEL
RING BOLT NUT
TORQUE WRENCH (TIGHTEN
WITH 75 TO 85 FT. LBS.
TORQUE)
FLYWHEEL RING AND
PRESSURE PLATE ASSEMBLY
WOOD BLOCK
2. TIGHTENING FLYWHEEL TO FLYWHEEL RING BOLT NUTS
DRIVING PLATE SEPARATOR
STUDS AND LOCK NUTS
SCREWDRIVER
WRENCH
3. ADJUSTING DRIVING PLATE SEPARATOR STUDS
RA PD 320028
Figure 252 — Installing Flywheel Ring and Pressure
Plate Assembly
244
ASSEMBLY OF SUBASSEMBLIES
TM 9-1725
79
l. Adjust Driving Plate Separator Studs. Tighten three driv-
ing plate separator studs until they just contact driving plate. Back
off Studs one complete turn to provide necessary % 6 -inch clearance,
and tighten studs with lock nuts (fig. 252).
m. Install Clutch Spindle Flange. Reinstall flange on spindle
(fig. 17). Install flat washer and flange nut, and tighten nut. Secure
nut with cotter pin. The engine is now completely assembled, ready
for test run. .
245
TM 9-1725
80-82
ORDNANCE MAINTENANCE - ORDNANCE ENGINE
MODEL R975-C4 (CONTINENTAL)
c
CHAPTER 6
TESTS AND ADJUSTMENTS
Paragraph
Preliminary instructions 80
Test schedule 81
Test procedure 82
Final adjustments 83
80. PRELIMINARY INSTRUCTIONS.
a. General. Test engine after each complete overhaul to “run-in”
new parts, and to see if engine operates satisfactorily. Attach engine
to suitable dynamometer stand. If dynamometer equipment is not
available, use a calibrated test club propeller designed to absorb 440
brake horsepower at 2,400 revolutions per minute. Also use a positive
type pressure gage for measuring oil pressure. Before starting engine,
check all items vital to safe operation such as, fuel lines and oil lines,
oil supply, magneto ground wires, throttle controls, and mounting
bolts. Have fire extinguishers handy.
81. TEST SCHEDULE.
a. Operate engine under loads specified in test schedule below.
Period
Time
Min.
R.P.M.
Observed
H.P.
(Approx.)
Fuel Flow
Lb/Hr
(Approx.)
Absolute
Manometer
Pressure
(In. of Hg.)
(Approx.)
i
10
Warm up to
1,200 rpm
•
2
10
1,200
55 .
40
16-17
3
10
1,500
107
65
18-19
4
15
1,600
130
80
20-21
5
15
1,700
156
95
21-22
6
15
1,800
185
110
23-24
7
20
1,900
208
120
24-25
8
20
2,000
254
132
26 — 27
9
20'
2,100
294
190
28-29
10
30
2,200
339
220
31-32
11
30
2,300
386
260
34-35
12
5
2,400 F.T.
440
310
37-38
13
30
97.5 percent (2340) :
93 percent (408)
274
35-36
14
10
Cool off period.
82. TEST PROCEDURE.
a. Make Entries on Inspection Log. Before starting engine,
enter number of carburetor and magnetos on inspection log ac-
companying engine.
246
TM 9-1725
82-83
TESTS AND ADJUSTMENTS
b. Start Engine. Start engine and enter time, initial speed, oil
pressure and oil-in temperature on log sheet. Operate engine for
period of time indicated in Test Schedule (par. 81).
c. Check Cylinder Firing. After starting engine, check cylinder
firing, and adjust carburetor idle mixture if necessary. To check
cylinders for firing, examine cylinder exhaust stacks. Flame from
stack indicates cylinder is firing. A red colored stack indicates heavy
oil consumption, a blue stack (the ideal condition) indicates low oil
consumption for that cylinder. Shut off engine. Feel each cylinder.
A cool cylinder indicates that particular cylinder is not firing.
d. Make Test Run. Start and run engine for periods of time in-
dicated in Test Schedule (par. 81). Enter time, oil pressure, and
oil-in temperature at start of each period. Complete reading for each
period as soon as engine operation has become stabilized. During the
No. 11 test period, take three complete readings. Readings should
approximate figures shown in test schedule. During period No. 12,
run engine at full throttle for 5 minutes and determine proper load
for period No. 13. Take three complete readings during period No. 13
for oil consumption check.
83. FINAL ADJUSTMENTS.
a. Oil Pressure Adjustment. After 1 hour (after period No. 5)
or at 1,800 revolutions per minute, reset oil pressure to 65 pounds.
The oil-in temperature should be between 160° and 180°F. Remove
oil pressure relief valve adjusting screw cap. Hold wrench (41-W-
1577-400) on relief valve body, and loosen lock nut. Tighten relief
valve body in pump. When engine is stabilized at 1,800 revolutions
per minute, adjust oil pressure to 65 pounds by turning adjusting
screw. When correct setting has been obtained, hold the adjusting
screw from turning, and tighten lock nut securely. Just previous to
period No. 12, with engine speed stabilized at 2,400 revolutions per
minute, adjust oil pressure to 75 pounds. Lock relief valve adjusting
screw, install new gasket, and replace relief valve cap. Lock wire
parts together securely.
b. Magneto Checks. Make final magneto adjustment at start of
test run. Check magnetos with test light. Magnetos should reach
their peak advance at engine speed of 1,500 revolutions per minute.
If either magneto does not reach its peak advance at 1,500 revolutions
per minute, reset it until it does. Make two further magneto checks,
one during period No. 9 and one after period No. 13 with the engine
operating at 2,400 revolutions per minute. In these checks, engine
speed should not drop more than 100 revolutions per minute when
the engine is switched from one magneto to the other. If engine
speed drops more than 100 revolutions per minute, reset magnetos.
247
TM 9-1725/
83
ORDNANCE MAINTENANCE - ORDNANCE ENGINE
MODEL R975-C4 (CONTINENTAL)
c. Set Governor. Set governor at end of test run. Stop engine,
and turn governor speed adjusting screw to the left to reduce governor
spring tension to a minimum. Start engine. Open throttle wide.
Engine speed should not exceed 2,400 revolutions per minute with the
adjusting screw turned to the left. Turn speed adjusting screw to the
right, to increase tension of the governor spring until tachometer reg-
isters from 2,200 to 2,250 revolutions per minute. Lock governor
adjustment. Test governor by closing engine throttle to drop engine
to idling speed. Then open throttle wide. Engine speed should not
exceed 2,400 revolutions per minute. After governor has been ad-
justed, make check to see that there is no engine surge at various
engine speeds. To insure close regulation (60 to 150 rpm) between
“no-load” and “full-load”, bring governor linkage eye bolt up as far as
necessary to insure close regulation without encountering surge. Do
not regulate governor to get a closer regulation than 60 revolutions
per minute, or surging will develop under different running or load
conditions. A 75 to 100 revolutions per minute regulation is highly
desirable, but not always possible to obtain. For this reason, a 150
revolutions per minute drop is permissible.
248
TM 9-1725
84-85
CHAPTER 7
FITS AND TOLERANCES
Paragraph
Front and main crankcase sections and front main bearing
support 84
Cylinder assemblies, valves, and valve mechanisms 85
Crankshaft, master rod, articulated rods, and knuckle pins .... 86
Diffuser section 87
Rear crankcase section and accessories 88
Oil pump 89
Flywheel and fan assembly 90
84. FRONT AND MAIN CRANKCASE SECTIONS AND FRONT
MAIN BEARING SUPPORT.
•
Replace
Beyond
Minimum
Maximum
Crankshaft thrust bearing nut and oil
seal ring, side clearance . . *
0.0 10L
0.002L
0.006L
Front crankcase section cover and
cover sleeve, diameter
0.003T
0.006T
Front crankcase section cover clamp
and thrust bearing, shim
0.005T
0.007T
Front main bearing and bearing ring,
diameter
0.0002T
0.00 15L
Front main bearing support and bear-
ing ring, diameter
0.003T
0.006T
Front main bearing support and front
crankcase section, diameter
0.003T
0.003L
Front main bearing support and main
crankcase section, diameter
0.006L
0.000
0.006L
Thrust bearing, total end movement .
0.020
0.006
0.010
85. CYLINDER ASSEMBLIES, VALVES, AND VALVE
MECHA-
NISMS.
a. Cylinders.
Cylinder barrel, choke
0.004
0.008
0.010
b. Piston Assemblies. .
Piston and piston pin, diameter
0.003L
0.000
0.00 1L
Piston, cast, center of skirt and cylin-
der, diameter
0.035L
0.015
0.019
Piston, forged, center of skirt and
cylinder, diameter
0.035L
0.025
0.029
Piston groove No. 1 (top) and ring,
side clearance
0.005 5L
0.007L
Piston groove No. 2 and ring, side
clearance
0.004L
0.0055L
249
TM 9-1725
85
ORDNANCE MAINTENANCE — ORDNANCE ENGINE
MODEL R975-C4 (CONTINENTAL)
Piston groove No. 3 and ring, side
Replace
Beyond
Minimum Maximum
clearance
Piston groove No. 4 and ring, side
0.0025L
0.004L
clearance
Piston groove No. 5 and ring, side
0.0025L
0.004L
clearance
0.0025L
0.004L
Piston pin and bushing, diameter .
0.005L
0.0015L
0.0025
Piston pin and plug
Piston pin bushing, and master and
0.005L
0.00 15L
0.0025
articulated rods, diameter
0.0045T
0.0065T
NOTE: Piston pin plugs assembled
in piston pin and cylinder bore.
Replace flat spot in excess of % 6 -inch diameter wear on
plug.
c. Rocker Arm Assemblies.
Rocker bearing bore and rocker bolt,
radius of
diameter
Rocker bearing, outside diameter, and
0.01 1L
0.000
0:00 1L
rocker arm, diameter
0.00 IT
0.002T
Rocker bolt and rocker box, diameter
Rocker box and rocker bearing, clear-
0.0005L
0.003L
ance before clamping
Rocker roller and rocker arm, side
0.010L
0.004L
0.0 10L
clearance
0.0025L
0.0095L
0.0155L
Rocker roller hub and pin, diameter
Rocker roller hub and rocker arm,
side clearance
0.0025L
rivet tight
0.0025L
Rocker roller hub and roller, diameter
d. Valve Mechanisms.
Valve guide and cylinder head, in-
0.005L
0.0015L
0.0035L
take, shrink fit
Valve guide and cylinder head, ex-
0.00 IT
0.0025T
haust, shrink fit
Valve guide and valve, intake, di-
0.002T
0.0035T
ameter
Valve guide and valve, exhaust, di-
0.0035L
0.0013L
0.0028L
ameter
Valve seat and cylinder head, intake,
0.0065L
0.0035L
0.0005L
shrink fit
Valve seat and cylinder head, ex-
0.0 14T
0.0 17T
haust, shrink fit
Valve spring, outer, diameter of wire,
0.192 inch
0.01 IT
0.015T
Weight at 1.34-inch height
90 lb
94.8 lb
104.8 lb
250
TM 9-1725
85-86
FITS AND TOLERANCES
Replace
Beyond
Minimum
Maximum
Weight at 1.96-inch height
501b
54.5 lb
86.5 lb
Valve spring, intermediate, diameter
of wire, 0.162 inch
Weight at 1.40-inch height
69 lb
73.0 lb
80.6 lb
Weight at 1.96-inch height
381b
42.0 lb
51.5 lb
Valve spring, inner, diameter of wire,
0.120 inch
Weight at 1.32-inch height
35 lb
38.6 lb
42.6 lb
Weight at 1.88-inch height
201b
22.4 lb
27.4 lb
Valve tappet ball socket spring, di-
ameter of wire, 0.05 1 inch
Weight at 2.18-inch height
61b
7.74 lb
9.46 lb
Valve tappet guide and crankcase
section, diameter
0.00 IT
0.003T
Valve tappet guide and valve tappet,
diameter
0.003L
0.0005
0.0015L
Valve tappet roller and roller pin,
diameter
0.006L
0.003L
0.0045L
e. Cam Assembly.
Cam and cam drive pinion, backlash
0.020
0.006
0.014
Cam and cam bearing, diameter . . .
0.0015T
0.0045T
Cam and cam hub and attaching
rivet, diameter before assembly . . .
0.000
0.006L
Cam drive pinion spring, wire di-
ameter 0.062 inch
Weight at 1.375-inch height
61b
81b
Cam hub end clearance
0.0 16L
0.009L
0.0 16L
Cam hub and cam bearing, diameter
0.00 15T
0.0045T
Cam hub support and cam bearing,
diameter
0.008
0.003L
0.005L
86. CRANKSHAFT, MASTER ROD, ARTICULATED RODS,
AND KNUCKLE PINS,
a. Crankshaft and Crankshaft Gear.
Crankpin bearing and crankpin, di-
ameter 0.006L
0.002 5L
0.004L
Crankpin bearing and master rod,
diameter, shrink fit
0.00 IT
0.003T
Crankshaft and crankshaft gear, di-
ameter ".
0.0005L
0.002L
Crankshaft and front main bearing,
diameter
0.0002T
0.0007T
Crankshaft and thrust bearing, di-
ameter
0.0002T
0.0009T
251
TM 9-1725
86
ORDNANCE MAINTENANCE - ORDNANCE ENGINE
MODEL R975-C4 (CONTINENTAL)
Replace
Beyond
Minimum
Maximum
Crankshaft bearing and main crank-
case section, diameter
Crankshaft bearing and rear crank-
0.002L
0.004T
shaft, diameter
0.0055L
0.002L
0.004L
Crankshaft cheek and flange of rear
main bearing, clearance
Crankshaft clamping cap screw elon-
0.025
0.040
gated
Crankshaft front and rear sections,
0.005
0.007
diameter before tightening clamp-
ing cap screw
0.00 1L
0.00 IT
0.00 1L
Crankshaft gear hub and crankshaft
gear, diameter
Crankshaft gear hub and crankshaft
0.005L
0.00 1L
0.003L
gear, side clearance .
Crankshaft gear spring, wire diameter
0.0 10L
0.003L
0.005L
0.1251 inch
Weight at 0.713-inch height
Crankshaft rear end plug and crank-
0.1701b
1811b
1911b
shaft, diameter
Crankshaft run-out between threads
0.000
0.002T
and splines at forward end when
supported at front and rear main
bearing (full indicator reading) .
0.004
Crankshaft run-out at center bearing
journal when supported at thrust
and rear main bearings (full indica-
tor reading)
0.004
■
Crankshaft run-out at thrust bearing
\
\
journal when supported at front
main bearing and rear main bear-
ing (full indicator reading)
0.004
Crankshaft spline, side clearance.
Movement of hub on crankshaft
measured at 15-inches, radius from
center of crankshaft
0.050
0.040
Rear crankshaft and counterweight
pin bushing, diameter
Rear crankshaft and counterweight,
0.00 IT
0.0025T
side clearance, total
Rear crankshaft counterweight and
0.015L
0.006L
0.012L
bushing, diameter
Rear crankshaft counterweight and
0.0015T
0.003T
stop, clearance
0.060L
0.04 1L
0.05 7L
252
TM 9-1725
86-87
FITS AND TOLERANCES
b. Master Rod.
Master rod, end clearance on crank-
pin
Master rod, maximum twist or mis-
alinement
Replace
Beyond Minimum Maximum
0.017L 0.019L
0.0045 in 6 inches
c. Articulated Rods.
Articulated rod, maximum twist or
misalinement 0.0045 in 6 inches
d. Knuckle Pins.
Knuckle pin and master rod, diameter 0.000
Knuckle pin bushing and articulated
rod, diameter
Knuckle pin bushing and knuckle pin,
diameter 0.004
Knuckle pin bushing and master rod,
side clearance 0.020L
Knuckle pin locks. Select locks to
obtain a light tapping fit when as-
sembled between knuckle pins.
0.000 0.008T
0.0045T 0.0065T
0.00 15L 0.0025L
0.006L 0.0 14L
87. DIFFUSER SECTION.
a. Diffuser Section.
Diffuser section and accessory drive
shaft bushing, diameter
0.00 IT
0.003T
Diffuser section shoulder and diffuser
ring, diameter
0.003L
0.007L
b. Starter Shaft and Gear.
Starter drive and crankshaft gear,
backlash
0.020
0.008
0.016
Starter drive gear and bushing, di-
ameter
0.006L
0.0025L
0.004L
Starter drive gear bushing and dif-
fuser section, diameter
0.00 IT
0.003T
Starter shaft, end clearance
0.050L
0.0 13L
0.045L
Starter shaft bushing and rear crank-
case section, diameter
0.00 IT
0.003T
Starter shaft bushing and shaft, di-
ameter
0.006L
0.0025L
0.004L
c. Impeller Assembly.
Impeller and shaft. Impeller must
be tight fit on splines.
Impeller and impeller housing, front
clearance 0.032 . 0.022 0.032
253
TM 9-1725
87-88
ORDNANCE MAINTENANCE - ORDNANCE ENGINE
MODEL R975-C4 (CONTINENTAL)
Replace
Beyond Minimum Maximum
Impeller drive gear hub, bearing and
impeller drive gear bushing, di-
ameter
0.006L
0.003L
0.004L
Impeller drive gear hub bearing, be-
tween shaft support and diffuser
section
0.000
0.008T
Impeller drive gear pinion and bear-
ing
0.025L
O.OOfcL
0.016L
Impeller drive pinion and crankshaft
gear backlash
0.025
0.010
0.018
Impeller intermediate gear and bush-
ing, diameter
0.00 IT
0.003T
Impeller oil seal ring, gap
0.008
0.000
0.006
Impeller oil seal ring, side clearance
0.010L
0.006L
0.008L
Impeller shaft and ball bearing, di-
ameter
0.0001
0.0004T
Impeller shaft bearing support and
bearing, diameter
0.0015L
0.0005L
0.00 13L
Impeller shaft gear and drive gear,
backlash
0.012
0.002
0.008
Impeller shaft nut lock and nut, end
clearance
0.002 L
0.000
0.002 L
Impeller shaft nut lock, side clear-
ance
0.000
0.003
Impeller shaft rear ball bearing, side
clearance
0.006L
0.004L
0.006L
Impeller shaft rear bearing and cage,
diameter 0.0015L 0.0005L 0.0013L
88. REAR CRANKCASE SECTION AND ACCESSORIES.
a. Accessory Drive Shaft.
Accessory drive idler gear, end clear-
ance
0.030L
0.01 1L
0.02 1L
Accessory drive idler gear and bush-
ing, diameter
0.006L
0.0025L
0.0045L
Accessory drive idler gear bushing
and diffuser section, diameter ...
0.0011
0.003T
Accessory drive gear and tachometer
and fuel pump drive shaft adapter,
diameter
0.005L
0.0015L
0.0035L
Accessory drive housing and rear
crankcase section, diameter
0.005L
0.00 1L
0.003L
Accessory drive shaft and bushing,
diameter
0.008L
0.0025L
0.0045L
254
FITS AND TOLERANCES
TM 9-1725
88
Accessory drive shaft and rear bush-
Replace
Beyond
t Minimum
Maximum
ing, diameter
Accessory drive shaft bevel gear and
0.006L
0.0025L
0.0045L
accessory drive gear, backlash. . . .
Accessory drive shaft bushing and
0.020
0.004
0.012
crankcase rear section, diameter. .
Accessory drive shaft rear bushing
and crankcase rear section, di-
0.003L
0.000
0.002L
ameter
Accessory idler, starter, and acces-
0.00 IT
0.003T
sory drive gear, backlash
0.020
0.004
0.012
Magneto shaft, end clearance
b. Fuel Pump Assembly.
Fuel pump adapter and accessory
0.035
0.012
0.035
drive housing, diameter
Fuel pump adapter and bushing, di-
0.0005L
0.0025L
ameter
Fuel pump adapter bushing and fuel
0.0025T
0.0045T
pump drive gear, diameter
Fuel pump drive gear and thrust plug
0.006L
0.002L
0.004L
retainer, diameter
Fuel pump drive gear and vacuum
0.003L
0.0005L
0.0015L
pump drive shaft, backlash
Fuel pump drive gear thrust plug
spring, wire diameter 0.046 inch
0.020
0.004
0.012
Weight at 0.0560-inch height . .
Fuel pump drive shaft and drive
81b
8.9 lb
9.11b
shaft bushing, diameter
Fuel pump drive shaft bushing and
0.006L
0.0025L
0.0045L
drive shaft housing, diameter ....
Fuel pump drive gear and bushing,
0.00 IT
0.003T
diameter
Fuel pump drive gear and extension,
0.005L
0.00 1L
0.003L
diameter
Fuel pump drive gear bushing and ac-
0.000
0.002T
cessory drive housing, diameter . . .
Fuel pump drive shaft adapter and
0.00 15T
0.0035T
accessory drive housing, diameter
Fuel pump drive shaft adapter and
0.0005L
0.0025L
bushing, diameter
Fuel pump drive shaft and adapter
0.0035T
0.0055T
bushing, diameter
Fuel pump drive shaft and collar,
0.005L
0.0016L
0.0036L
diameter
0.0005T
0.0025T
255
TM 9-1725
88
ORDNANCE MAINTENANCE - ORDNANCE ENGINE
MODEL R975-C4 (CONTINENTAL)
Replace
Beyond
Minimum
Maximum
Fuel pump drive shaft and vacuum
pump drive gear, backlash
o;o 2 o
0.004
0.012
c. Generator Drive and Idler Gears.
Generator drive gear and bushing,
diameter 0.007
0.0025
0.0055
Generator drive gear and generator
drive gear support, end clearance
0.006L
0.02 0L
Generator drive gear and generator
drive intermediate gear, backlash
0.020
0.004
0.012
Generator drive gear support and
bushing, diameter
0.007
0.0025
0.0055
Generator drive gear support and rear
crankcase section
0.00 IT
0.003L
Generator drive intermediate and
generator intermediate gear sup-
port bushing, diameter
0.006
0.00 15L
0.0045
Generator drive intermediate gear
and generator drive support
0.045L
0.006L
0.030L
Generator idler gear and bushing,
diameter
0.0005T
0.0035T
Generator idler gear and starter gear,
backlash
0.020
0.004
0.012
Generator idler gear bushing and
shaft, diameter
0.005L
0.00 1L
0.003L
Generator idler gear, end clearance .
0.035
0.003L
0.023
Generator idler gear shaft and bush-
ing, diameter
0.005L
0.00 1L
0.003L
Generator idler gear shaft and rear
crankcase section, diameter
0.000
0.002L
Generator idler gear shaft bushing
and rear crankcase section, diam-
eter
0.00 IT
0.003T
Generator intermediate gear and gen-
erator idler gear, backlash
0.020
0.004
0.012
Generator intermediate gear support
and bushing, diameter
0.00 IT
0.003T
d. Rear Crankcase Section.
Rear crankcase section and packing
retainer ring, diameter
0.00 IT
0.004T
Rear crankcase section, tachometer,
and three-way accessory drive
shaft adapter, large diameter ....
0.00 1L
0.005L
256
FITS AND TOLERANCES
TM 9-1725
88-89
e. Tachometer Drive.
Tachometer and fuel pump drive
shaft and adapter cover bushing,
Replace
Beyond
Minimum
Maximum
diameter
Tachometer and fuel pump drive
0.004
0.0005L
0.0025L
shaft adapter and cover, diameter
Tachometer and fuel pump drive
shaft adapter, cover, and bushing,
0.0005L
0.002 5L
diameter
Tachometer, fuel pump drive shaft
adapter, and rear crankcase section,
0.0005L
0.0025L
small diameter
Tachometer and fuel pump drive
shaft and vacuum pump drive gear,
0.000
0.002L
backlash
Tachometer and fuel pump drive
shaft and accessory drive gear,
0.020
0.004
0.012
diameter
Tachometer drive gear and drive-
0.005L
0.001L
0.003L
shaft gear, backlash
Tachometer drive gear and housing,
0.020
0.004
0.012
end clearance
Tachometer drive gear and sleeve and
0.002L
0.052L
tachometer shaft bushing, diameter
Tachometer drive gear and tachom-
0.0005L
0.0035L
eter drive gear sleeve
89. OIL PUMP.
Governor drive gear and governor
0.0005T
0.0035T
shaft gear, backlash
Oil pressure pump body and oil pump
0.018
0.004
0.012
idler shaft, end clearance
Oil pressure pump body and oil pump
0.005L
0.00 1L
0.002 5L
idler shaft, side clearance
Oil pressure relief valve seat and oil
0.005
0.002
0.0035
pump, diameter
Oil pressure relief valve spring, wire
diameter 0.051 inch, weight at 1.25-
0.0023T
0.0038T
inch height
Oil pump body governor drive shaft
41b
4.95 lb
6.05 lb
bushing, diameter
Oil pump body and oil pump drive
0.0035L
0.00 IT
0.0025T
shaft, diameter
Oil pump body and oil pump idler
0.0035L
0.00 1L
0.0025L
gear, side clearance
0.005L
0.002L
0.0035L
257
TM 9-1725
89-90
ORDNANCE MAINTENANCE - ORDNANCE ENGINE
MODEL R975-C4 (CONTINENTAL)
Replace
Beyond
Minimum
Maximum
Oil pump body and oil pump idler
shaft, diameter
0.0025
0.001L
0.0025L
Oil pump body and pump gear, side
clearance
0.005L
0.002L
0.0035L
Oil pump body bushing and governor
drive shaft, diameter
0.005L
0.00 1L
0.003L
Oil pump drive gear and oil pressure
pump body, diameter
0.003L
0.001L
0.003L
Oil pump drive shaft and oil pump
gear spacer, diameter
0.0025L
0.0071
0.00 17L
Oil pump drive shaft and oil pressure
pump body, diameter
0.003L
0.00 1L
0.002 L
Oil pump drive shaft and oil pump
idler shaft, backlash
0.007
0.002
0.005
Oil pump drive shaft gear and oil
pressure pump body, side clear-
ance
0.0035L
0.002L
0.0035L
Oil pump gear and oil pump idler
gear, backlash
0.008
0.004
0.006
Oil pump idler gear and body, end
clearance
0.005L
0.002 L
0.0035L
Oil pump idler shaft and oil pressure
pump body, diameter
0.003L
0.00 1L
0.002 5L
Oil pump idler shaft and pump spacer,
diameter
0.0025L
0.0007L
0.00 17L
Oil suction strainer spring, wire diam-
eter 0.063 inch, weight at 3.125-
inch height
51b
61b
90. FLYWHEEL AND FAN ASSEMBLY,
a. Flywheel.
Diameter of driving pin
0.7525
0.7535
b. Flywheel Hub.
Inside diameter of hub
2.631
2.638
Inside diameter of splines
2.412
2.419
Diameter of rear spindle bearing seat
3.5055
3.5063
Inside diameter of rear spindle bear-
ing
3.506
3.506
258
TM 9-1725
91-92
CHAPTER 8
TOOLS
Paragraph
Common tools 91
Special tools 92
91. COMMON TOOLS.
a. Lists of common tools ordinarily required for work on the
R975C-4 engine will be found in SNL N-19 and SNL N-21.
92. SPECIAL TOOLS.
a. Special tool sets required for operations ordinarily performed by
organizational mechanics are listed in SNL G-19. SNL G-27 lists
standard maintenance tool sets for use by automotive ordnance main-
tenance establishments. In addition, it lists special tools designed
specifically for repair of this engine. The special tools required for
the operations described in this manual are listed below:
Federal Stock Manufacturer's
TOOL Number Number
BAR, crankshaft alining, 0.4995-in.
diameter; selective fit No. 1 41-B-150-25 MTM-M3-216
BAR, master and articulating rod,
piston pin bushing, finish bore
alinement checking, 1.2495-in.
diameter; selective fit No. 2 41-B-263 MTM-M3-349
BAR, master rod crankshaft bearing,
finished bore alinement, 2.2525-in.
diameter 41-B-263-27 MTM-M3-353
BAR, master rod crankshaft bearing,
finished bore alinement, 2.2530-in.
diameter 41-B-263-29 MTM-M3-354
BAR, valve tappet guide, installing . 41-B-332 MTM-M3-261
COMPRESSOR, piston ring, special
5-in. diameter 41-C-2550-80 MTM-M3-207
COMPRESSOR, valve spring 41-C-2559-25 MTM-M3-260
CONE, accessory drive shaft, leather
oil seal, installing 41-C-2562-11 MTM-M3-436
DRIFT, accessory drive shaft, leather
oil seal, installing 41-D-1460 MTM-M3-427
DRIFT, piston (round fiber) 41-D-1541-75 MTM-M3-330
EYE, crankshaft and engine lifting . 41-E-615 MTM-M3-208
FIXTURE, accessory drive shaft
bushing, diffuser section, and rear
crankcase section holes, line ream 41-F-2987-210 MTM-M3-345
FIXTURE, boring master and articu-
lating rod bearing , 41-F-2987-425
FIXTURE, rear bearing, recondition-
ing, with reamers 41-F-2994-21 MTM-M3-376
259
TM 9-1725
92
ORDNANCE MAINTENANCE - ORDNANCE ENGINE
MODEL R975-C4 (CONTINENTAL)
TOOL
FIXTURE, timing including disk
pointer and handle (bare engine)
GAGE, plug, valve tappet guide.
GAGE, cylinder bore, star
GAGE, plug, no-go, exhaust valve
guide, 0.6295 in
GAGE, thickness, special, 0.010 in.
and 0.070 in
HONE, valve tappet guide
INDICATOR, piston, top dead cen-
ter, dial type (with box)
PLUG and COLLAR, master rod
crankshaft bearing removing and
installing
PULLER, crankcase section removing
(3 per engine required)
PULLER, crankshaft rear end plug
PULLER, knuckle pin
PULLER, leather oil seal, accessory
drive
REAMER, carbon steel, accessory
drive shaft short and long bushing
hand line ream, standard size
REMOVER and REPLACER, bear-
ing, crankshaft, rear
REAMER and BUSHING, starter
shaft and starter drive gear bushing
RING, checking cylinder bore diam-
eter (use w/41 G-99-500)
ROLLERS, crankshaft alinement
STAND, crankshaft assembly and
disassembly
STAND, master and articulating rod
hole alinement checking
STAND, valve removing and install-
ing ■ ■
TOOL, impeller shaft and front nut,
locking
TOOL-SET, piston pin and knuckle
bushing replacement
WRENCH, generator removing
WRENCH, crankshaft gear hub
screw (O.D. 0.550-0.555)
Federal Stock
Number
41-F-2997-84
41-G-99-500
41-G-254-285
41-G-412-75
41-1-73-110
41-P-2 115-500
41-P-2906-280
41-P-2907-100
41-P-2941-125
41-P-2951-11
41-R-390
41-R-2373-675
41-R-2324
41-R-2492
41-R-2660
41-S-4932
41-S-4977
41-S-4988-77
4 l-T-32 17-100
41-T-3539-8
41-W-636-550
41-W-871-31
Manufacturer's
Number
MTM-M3-221
MTM-M3-468
MTM-M3-2 1 1
MTM-M3-237
MTM-M3-317
MTM-M3-359
MTM-M3-2 96
MTM-M3-362
MTM-M3-298
MTM-M3-342
WR-81014
MTM-M3-316
MTM-M3-423
MTM-M3-288
MTM-M3-527
MTM-M3-350
MTM-M3-2 14
MTM-M3-417
MTM-M3-384
MTM-M3-294
260
TOOLS
Federal Stock
TOOL Number
WRENCH, crankshaft thrust bearing
nut 41-W-871-35
WRENCH, cylinder hold-down nut,
%6-in. hex. (EC-3 only) 41-W-872-375
WRENCH, intake pipe packing nut 41-W-1537
WRENCH, oil pump to crankcase
rear section attaching nut, % e-in-
hex 4 1-W- 15 77-500
WRENCH, push rod housing clamp
screw (flexible) 41-W-1986
WRENCH, clutch spindle flange 41-W-3058-300
WRENCH, rear cylinder attaching
nuts
TM 9-1725
92
Manufacturer's
Number
MTM-M3-297
MTM-M3-287
MTM-M3-210
MTM-M3-299
MTM-M3-483
261
TM 9-1725
ORDNANCE MAINTENANCE - ORDNANCE ENGINE
MODEL R975-C4 (CONTINENTAL)
REFERENCES
STANDARD NOMENCLATURE LISTS.
Cleaning, preserving and lubricating materials;
recoil fluids, special oils, and miscellaneous
related items SNL K-l
Soldering, brazing, and welding material, gases,
and related items SNL K-2
Tools, maintenance, for repair of automotive ve-
hicles SNL G-27
VoL 1
Interchangeability chart of ordnance mainte-
nance tools for combat vehicles SNL G-27
Vol. 2
Tool-sets, motor transport SNL N-19
Tool-sets for ordnance service command, auto-
motive shops SNL N-30
General tools and supplies, ordnance base auto-
motive maintenance company (engine re-
build) SNL N-327
Current Standard Nomenclature Lists are listed
above. An up-to-date list of SNL’s is main-
tained in the Index to Ordnance Publica-
tions ASF CAT. ORD-2 OPSI
EXPLANATORY PUBLICATIONS.
Military motor vehicles AR 850-15
List of publications for training FM 21-6
Related Technical Manuals.
Ordnance maintenance: Accessories for Wright
R975EC-2 engines for medium tanks M3 and
M4 TM 9-1750D
Ordnance maintenance : Electrical equipment
(Delco Remy) TM 9-1825A
Ordnance maintenance : Electrical equipment
(Auto-Lite) TM 9-1825B
Ordnance maintenance: Carburetors (Strom-
berg) TM 9-1826B
Ordnance maintenance: Fuel pumps TM 9-1828A
Automotive Materiel.
Automotive electricity TM 10-580
Electrical fundamentals TM 1-455
262
TM 9-1725
REFERENCES
Fuels and carburetion
The internal combustion engine
The motor vehicle
Care and Preservation.
Automotive lubrication
Cleaning, preserving, lubricating, and welding
materials and similar items issued by the Ord-
nance Department
Explosives and demolitions
Motor transport inspections
Product guide
Decontamination.
Chemical decontamination materials and equip-
ment
Decontamination of armored force vehicles ....
Defense against chemical attack
Storage and Shipment.
Registration of motor vehicles
Rules governing the loading of mechanized and
motorized army equipment, also, major caliber
guns, for the United States Army and Navy, on
open top equipment published by Operations
and Maintenance Department of Association
of American Railroads
Storage of motor vehicle equipment
Ordnance field service storage and shipment
Chart — group G major items . %
0
TM 10-550
TM 10-570
TM 10-510
TM 10-540
TM 9-850
FM 5-25
TM 10-545
OFSB 6-2
TM 3-220
FM 17-59
FM 21-40
AR 850-10
AR 850-18
OSSC-G
263
TM 9-1725
ORDNANCE MAINTENANCE - ORDNANCE ENGINE
MODEL R975-C4 (CONTINENTAL)
INDEX
A Page No.
Accessory drive gears
installation 199
removal 65-67
replacement 154
Accessory drive housing, three-way
assembly 182
cleaning, inspection, repair 182
installation 205
removal 163-165
Accessory drive mechanism de-
scription 16-19
Accessory drive shafts
fits and tolerances 254-255
installation , 194-195
removal 167-168
Accessory drive, three-way, and
tachometer
assembly 184
cleaning 182
disassembly 182
installation 203
removal 167
Adjustments and tests. . . 178,246-248
Adjustment
governor 248
magneto 247
oil pressure 247
valves 227-229
Air deflectors, cleaning, inspection
and repair 192
Air deflectors, intercylinder, instal-
lation 220—223
Antifriction bearings, cleaning. . . 82
Articulated rods
fits and tolerances 253
installation 209
removal ^58-6 1
replacement 137
Articulated rods and knuckle pins '
assembly 140
cleaning 137
disassembly 136
inspection and repair 137-140
Assembly
articulated rods and knuckle pins 140
crankcase section
front 88,206-215
Page No.
main 97-100,206—215
rear 171
crankshaft 130-136
crankshaft gear assembly 141
cylinders 107-112
diffuser section 156—162
diffuser and rear crankcase sec-
tion 194—206
disassembly and assembly of
subassemblies 85
fan to flywheel 192
flywheel and fan . 191
front main bearing support 88
fuel pump and mounting 187
generator drive gear support . 181
generator idler gear and shaft 180
ignition harness 189-190
master rod 130—136
oil drain tubes 113
oil pump 176-178
pistons 117
starter gear and shaft . 180
tachometer drive assembly 185-186
three-way accessory drive hous-
ing 182
valve operating mechanism 107-112
B
Baffle attaching springs, removal 47
Body screws, replacement 176
Booster coil
installation 239
removal 39-40
Bushings, replacement 169-170
c
Cables to and from distributor
blocks
installation 190
removal 188
Cam assembly
installation 99-100
removal 64
Cam hub and ring assembly
inspection 95-97
installation 97
264
TM 9-1725
INDEX
C— Cont'd Page No.
Carburetor, removal 35
Carburetor elbow
installation 237—238
removal 162—163
Carburetor support bracket
installation 238
removal 35
Cigarette connectors, installa-
tion 189-190
Cigarette connector protectors, re-
moval 188
Clamping cap screw, removal . . 120
Cleaning
air deflectors 192
antifriction bearings 82
articulated rods and knuckle pins 137
cowling 192
crankcase section
front 86
main 89
rear . . 168-169
crankshaft gear assembly. . 125, 141
cylinders 104-105
diffuser section 144
disassembly and assembly of
subassemblies 82
engine supports 192
exhaust manifold collector
ring 192-193
flywheel and fan 190
main bearing support, front 86
fuel pump and mounting 187
generator idler gear and shaft 180
generator drive gear support . 181
ignition harness 188-189
master rod 125
oil pump 173
pistons 113-116
starter gear and shaft 179—180
sump assembly 193
tachometer drive assembly 184—185
three-way accessory drive hous-
ing 182
valve operating mechanisms 104-105
Clutch, flywheel and fan (See fly-
wheel, fan and clutch)
Clutch parts, removal ' 33
Clutch spindle flange
installation 245
removal 32
Page No.
Conduits, installation 189
Conduit at carburetor, removal 34-35
Cone, front and nut, installation 239
Cone, rear, installation 239
Connecting rod assemblies, descrip-
tion 14—15
Cover plates, removal 162
Cover crankcase section, rear in-
stallation 195—196
Cowling
cleaning, inspection and repair 192
description 10
removal 45
Crankcase breather
installation 235
removal 47—48
Crankcase sections
front
assembly 88,206-215
cleaning . . . , 86
description . . 8-10
disassembly 86
fits and tolerances 249
inspection and repair 86-88
installation 212-213
removal 56-58
main
assembly 97-100,206-215
cleaning 89
disassembly 88-89
inspection and repair 89-96
removal 62-63
rear
assembly 171
cleaning 168-169
disassembly 162-168
fits and tolerances 254-255
inspection 168-169
removal 69, 168
subassemblies 179-187
Crankcase sections, rear and dif-
fuser (See diffuser and crankcase
section )
Crankcase section, rear, on stand,
installation 194
Crankpin plug from crankpin, re-
moval 125
Crank plug, rear; removal 124
Crank, rear; removal 120
265
TM 9-1725
ORDNANCE MAINTENANCE - ORDNANCE ENGINE
MODEL R975-C4 (CONTINENTAL)
C— Cont'd Page No.
Crankshaft
assembly 130—136
cleaning 125
description 15-16
disassembly 119—125
fits and tolerances 251—252
inspection and repair 125—130
installation 206—207
removal 63—64
Crankshaft gear, removal 63
Crankshaft, front end
inspection 125-126
installation 124
Crankshaft gear assembly
assembly 141
cleaning 141
disassembly 140
inspection 141
Cylinders
assembly 107-112
cleaning 104-105
description 12
disassembly 100-104
fits and tolerances 249-250
inspection 105-112
installation 216-219
removal 52—53
Cylinder head air deflectors, in-
stallation 223
Cylinder head baffles, removal ... 50
Cylinder, No. 1, installation . . 217—219
Cylinder temperatures, data 28
D
Data
cylinder temperatures 28
engine lubrication system 29
engine, model R975-C4 (Con-
tinental) 27-29
fuel system 28-29
ignition . . 28
valves 27—28
Description
Page No.
engine lubrication system. . . . 22-27
engine, model R975-C4 (Con-
tinental) 8-27
fuel system 20-22
ignition system 20
pistons, piston pins and rings 12-13
valve operating mechanism. . 13-14
Diffuser section
assembly 156—162
cleaning 144
disassembly 141-143
fits and tolerances 253
inspection 144—154
installation 199
Diffuser section bushings, replace-
ment 149
Diffuser section, cover 206
Diffuser and rear crankcase sections
assembly 194—206
installation 194-206
Diffuser section from rear crank-
case section 67-69
Diffuser ring
installation 157-158
removal 143
Disassembly and assembly of sub-
assemblies
assembly 85
cleaning 82
inspection 82
repair 83-85
Disassembly of engine into sub-
assemblies
preliminary instructions . . . 30-32
Disassembly
articulated rods and knuckle pins 136
crankshaft ...... 119-125
crankshaft gear assembly 140
cylinders 100-104
disassembly and assembly of
subassemblies 82
diffuser section 141—143
flywheel and fan 190
accessory drive mechanism . 16-19 front crankcase section 86
connecting rod assemblies. . . 14—15 front main bearing support ... 86
cowling
10 fdel pump and mounting 187
crankcase 8-10 generator drive gear support . 181
crankshaft 15-16 generator idler gear and shaft. . 180
cylinders
12 ignition harness
188
266
TM 9-1725
INDEX
D— Cont'd Page No.
Disassembly — Cont’d
impeller bearing cage 142-143
main crankcase section 88-89
master rod 119—125
oil pump 171-173
pistons 113
rear crankcase section . . 162-168
starter gear and shaft 179
tachometer drive assembly. . . . 184
three three-way accessory drive
housing 181-182
valve operating mechanisms 100-104
Driven disk, inner and outer, in-
stallation 243
Driving plate, installation 243
Dynamic damper
inspection 127
installation 130—131
removal 124
test 127
E
Engine, model R975-C4 (Con-
tinental )
data 27-29
description 8-2 7
lubrication system
data 29
description 22-2 7
supports
cleaning, inspection and repair 192
rear, installation 237
rear, removal 43
support bar, installation, re-
moval 43-45, 233
Exhaust elbows
installation 113
removal 101
Exhaust manifold collector ring
cleaning, inspection and
repair 192-193
installation 237
removal 43
F
Fan assembly
fits and tolerances 258
inspection 191
Page No.
Fan assembly and flywheel
assembly 192
fits and tolerances 258
installation 239
removal 190
Fan, flywheel and clutch (See Fly-
wheel, fan and clutch)
Fits and tolerances
accessory drive shaft 254-255
articulated rods 253
crankcase sections
front and main 249
rear 256
rear and accessories 254-255
crankshaft 251—252
cylinder assemblies 249—250
diffuser section 253
fan assembly 258
flywheel 258
flywheel hub 258
front main bearing support. . 249
fuel pump assembly 255-256
impeller assembly 253-254
knuckle pins 253
master rods 253
oil pump 257-258
piston assemblies 249-250
rocker arm assemblies 250
starter shaft and gear 253
tachometer drive 257
valves 249—250
valve mechanisms 250-251
Flywheel
fits and tolerances 258
inspection 191
Flywheel and fan
assembly 191
cleaning, inspection and
repair 190-191
disassembly 190
fits and tolerances 257
installation 239
removal 33
Flywheel hub, fits and tolerances 258
Flywheel fan and clutch, installa-
tion 239-245
Flywheel ring and pressure plate
installation 243
removal 32-33
267
TM 9-1725
ORDNANCE MAINTENANCE - ORDNANCE ENGINE
MODEL R975-C4 (CONTINENTAL)
F— Cont'd Page No.
Front bearing inner race and spacer,
removal 124
Fuel and drain lines
installation 238—239
removal 34
Fuel induction tubes
installation 223
removal 50-52
Fuel pump
fits and tolerances 255-256
installation 238
removal 35
Fuel pump and mounting
assembly 187
cleaning, inspection and repair 187
disassembly 187
Fuel system
data 28-29
description 20-22
G
Gears, installation 175-176
Gear spacer plate
removal 171-173
replacement 174
Generator, removal 41
Generator drive gear support
assembly 181
cleaning, inspection and repair 181
disassembly 181
installation 194
Generator idler gear, removal . 167
Generator idler gear and shaft
assembly 180
cleaning, inspection and repair 180
disassembly 180
installation 194
Generator support pad, removal 41—42
Governor
adjustment 248
installation 237
removal 42
Governor drive gear
installation 177
removal 173
Governor drive gear, intermediate,
removal 173
I Page No.
Idler gears
installation 162
removal 141
replacement 154
Ignition cables, installation 189
Ignition harness
assembly 189—190
cleaning, inspection and
repair 188-189
disassembly 188
installation 208-209
removal 61-62
test 190
Ignition system
data 28
, description 20
Impeller assembly
fits and tolerances 253—254
installation 161
removal 142
Impeller bearing cage
disassembly 142-143
installation 158
removal 142
Impeller drive gear assembly
installation . . 158-159
replacement 153-154
Impeller drive gear and shaft,
removal 142
Impeller drive gear shaft support,
removal 141
Impeller oil seal cage, removal . . . 143
Impeller shaft assembly, replace-
ment 153
Inlet screen assembly, replacement 175
Inspection
air deflectors 192
articulated rods and knuckle
pins 137-140
cam hub and ring assembly. . 95-97
cowling 192
crankshaft 125-130
crankshaft gear assembly 141
cylinders 107-114
diffuser section 144-154
disassembly and assembly of
subassemblies 82
“fengine supports 192
268
TM 9-1725
INDEX
I— Cont'd Page No.
Inspection — Cont'd
exhaust manifold collector
ring 192-193
fan 191
flywheel 191
front crankcase section 86-88
front main bearing support 86—88
fuel pump and mounting 187
generator drive gear support 181
generator idler gear and shaft 180
ignition harness 188—189
main crankcase section . . . . 89-96
master rod , 125—130
oil pump 174—176
pistons 116
piston pins 117
push rod assemblies 107
rear crankcase section . . 168—169
rear main bearing 90
rocker box assemblies 105-107
separator pins 191
separator springs 191
starter gear and shaft 179-180
sump assembly 193
tachometer drive assembly 184—185
three-way accessory drive hous-
ing 182
valve operating mechanisms 105-114
valve tappets 95
valve tappet guides 91-95
Intercylinder air deflectors, instal-
lation
220-223
Intercylinder baffle assemblies,
removal
52
Page No.
Magneto conduits
installation 190
removal 188
Magneto distributor block cover,
removal 41
Magneto elbows from ignition
cables, removal 188
Magneto shielding, removal . 36-39
Main bearing, front
installation 2,10—212
test 127-128
Main bearing, rear
inspection 90
replacement 90—91
Main bearing support, front
assembly 88
cleaning 86
disassembly 86
fits and tolerances 249
inspection and repair 86—88
installation 212
removal 58
Main and front crankcase sections,
assembly 206-215
Main crankcase section to rear
section, installation 208
Manifold ring, disconnection . .. 188
Master rod
assembly 130—136
cleaning 125
disassembly 119—125
fits and tolerances 253
inspection and repair ... 125-130
installation 206-207
removal 120-123
K
Knuckle pins
fits and tolerances 253
installation 209-210
replacement 140
L
Lock at rear of impeller shaft,
replacement 162
M
Magnetos
adjustment 247
installation 229-230
removal 41
replacement 128-130
Master rod spacer, removal . 123—124
o
Oil drain tubes
assembly 113
removal 104
Oil inlet strainer, removal 173
Oil pressure, adjustment 247
Oil pump
assembly 176-178
cleaning 173
disassembly 171—173
fits and tolerances 257-258
inspection and repair 174-176
269
TM 9-1725
ORDNANCE MAINTENANCE - ORDNANCE ENGINE
MODEL R975-C4 (CONTINENTAL)
O— Cont'd Page No.
Oil Pump — Cont'd
installation 202-203
removal 167
tests and adjustments 178
Oil pump drive gear, removal . . . . 171
Oil pump thermometer adapter,
removal 173
Oil rings, installation 160-161
Oil seal cage, installation . . 156-157
Oil standpipe, installation 195
Oil standpipe seal, installation . 206
P
Pistons
assembly 117
cleaning 113-116
disassembly 113
fits and tolerances 249-250
inspection and repair 116
removal 52-56
Piston, No. 1, installation . 216-217
Piston pins, inspection 117
Piston rings
installation . 117
removal 113
Pistons and cylinders, installa-
tion 219-220
Pistons, piston pins and rings
description 12-13
Pressure plate and flywheel ring,
installation ’ 243
Pressure pump body
installation 177-178
removal 171
replacement 174
Pressure pump body and spacer
plate assembly, installation 177
Pressure pump drive shafts,
installation 176
Primer system
installation 235-237
removal 47
Push rod assemblies
inspection 107
installation 224
Push rods and housings, removal 48—50
Push rod housings, installation .... 223
Push rod housing adapters
installation 97
Page No.
removal 65
Push rod sockets and springs,
removal 50
R
Rear crank, inspection and
test 126-127
Relief valve assembly
installation 178
removal 173
replacement .. 17 e
Repair
accessory drive housing,
three-way 182
air deflectors 192
cowling 192
engine supports 192
exhaust manifold collector
ring 192-193
flywheel and fan . 191
fuel pump and mounting 187
generator drive gear support 181
generator idler gear and shaft 180
ignition harness . . 188-189
starter gear and shaft 179-180
sump assembly 193
tachometer drive assembly 184-185
Rocker arm assemblies
fits and tolerances 250
installation 224-226
removal 48
Rocker box assemblies, inspec-
tion 105-107
Rocker box covers, removal 48
Rubber seals and spacers, installa-
tion 198
s
Scavenger gears, installation 176-177
Scavenger pump body, replace-
ment 174-175
Scavenger pump body cover
installation 178
removal 173
replacement 176
Separator pins
inspection 191
installation 239-243
removal 190
270
TM 9-1725
INDEX
S— Cont'd Page No.
Separator pin springs, removal . . 190
Separator springs, inspection. . . 191
Separator springs on flywheel, in-
stallation 191
Slit brass cone, removal 56
Strainer assembly, installation . 178
Spacers and rubber seals, installa-
tion 198
Spark plug conduits, removal . . 186
Spark plugs
front
installation 223
removal 46—47
rear, removal 52
Spark plug terminal elbows,
removal 188
Spindle, installation 243
Starter
installation 230-233
removal 40
Starter gear and shaft
assembly 180
cleaning, inspection and
repair 179-180
disassembly 179
' fits and tolerances 253
removal 65
Starter gear, installation . . . 200-202
Starter shaft hut, removal 52
Starter shaft seal
installation 194
removal 168
Sump assembly
cleaning, inspection and repair 193
installation 233-235
removal 46
Sump drain pipe and fitting,
removal 64
Sump fitting, installation 97
T
Tachometer and three-way acces-
sory drive
installation 203
removal 167
Tachometer drive assembly
assembly 185—186
cleaning, inspection and
repair 184-185
Page No.
disassembly 184
fits and tolerance 257
installation 203
removal 166-167
Tappet guides and rear bearing,
main 65
Tests and adjustments
final adjustments 24 7-248
preliminary instructions 246
test procedure 246-247
test schedule 246
Three-way accessory, drive housing,
installation 205
Three-way accessory drive, and
tachometer, removal 167
Throttle box
installation 238
removal 36
Thrust bearing, front, installation 213
Thrust bearing retaining nut,
removal 56
Thrust bearing spacer, installation 212
Thrust nut, front, installation 214-215
V
Valve operating mechanisms
description 13-14
fits and tolerances 250-251
installation 215^229
Valves
adjustment 227-229
assembly 107-112
cleaning 104-105
data 27-28
disassembly 105-114
fits and tolerances 249-250
inspection and repair 105-114
installation 113,227-229
removal 101-104
Valve springs, removal 101
Valve tappets
inspection 95
installation 97-99
removal 64—65
replacement 95
Valve tappet guides
inspection 91-95
replacement 95
RAPD1 8FEB44-41 M 271
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